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Local Governments • U.S. Department of Agriculture
It is the policy of the University of Maryland, College of Agriculture and Natural Resources, Maryland Agricultural Experiment Station, and University of
Maryland Extension that all persons have equal opportunity and access to programs and facilities without regard to race, color, gender, religion, national origin, sexual orientation, age, marital or parental status, or disability.
The University of Maryland Extension Agriculture and Food Systems and Environment and Natural Resources Focus Teams proudly present this publication for commercial vegetable and fruit industries.
Volume 11 Issue 3 June 11, 2020
Early Summer Insect Vegetable Scouting Guide
By Emily Zobel Agriculture Agent Dorchester County
As brassica crops get ready to be harvested, continue to check them for common caterpillar pests such as cabbage loopers, diamondback moths, and imported cabbageworms. From head to harvest, treat when 5% or more of the plants are infested with caterpillars. Avoid overuse of pyrethroids to prevent aphid flare-ups.
Cucumber beetles are out and moving into cucurbits crops. Spot treatments of field edges can help control populations early on. Consider planting Blue "Hubbard" squash as a trap crop around the edges of the field of wilt susceptible varieties, especially near woods.
Neonicotinoid seed treatments will provide control for about 2 weeks. The threshold for treating for cucumber beetles is 1 beetle per plant on wilt susceptible cucumbers, melons, Hubbard and butternut squash, and younger pumpkins, and 5 cucumber beetles per plant in watermelon, other varieties of squash, and older pumpkins (University of Wisconsin-Madison). High-density rows pickling cucumbers can compensate for at least 10% stand losses.
As we move into summer and the weather becomes hot and dry Two-Spotted spider mite infestations may be seen around field margins and grassy areas. Spot treat local infestations when possible. Treat when 10-15% of the crown leaves are infested early in the season, or when 50% of the terminal leaves are infested later in the season.
As early-season sweet corn starts to tassel and silk, scout for caterpillar in the whorls. Early tassel treatment is usually more effective than a whorl treatment because larvae are more exposed to the chemicals. For early season plantings, treat when 15% of the plants show fresh feeding signs.
White Rot of Onion and Garlic
By Jerry Brust Extension IPM Vegetable Specialist
& Karen Rane
Plant Diagnostic Lab University of Maryland
The weather we had in May was great for seed maggots and for some soil diseases. One very serious soil disease that affects Allium species, especially onion and garlic, is white rot, caused by the fungus Stromatinia cepivorum (syn. Sclerotium cepivorum (fig. 1)), which was found in the last few weeks in Maryland. White rot is NOT the same as white mold, which is caused by Sclerotinia sclerotiorum, which has a very large host range (tomatoes, peppers and 170 other plant species); white rot only infects Allium species.
Leaves of Allium plants with white rot exhibit yellowing, dieback, and wilting. Under ideal weather conditions, white mycelial growth can develop on the bulb. As the disease progresses, the mycelium becomes more compacted with numerous small, spherical black bodies (sclerotia) forming on this white mat (fig. 2). These sclerotia are the overwintering structures of the pathogen and are approximately the size of a pin head. As the disease progresses, these sclerotia are eventually released into the soil. Infected plant roots will rot, making the plant easily pulled from the soil. Disease
Fig. 1 White rot on garlic plant.
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Fig. 1 Distorted leaves of raspberry caused by broad mite feeding.
development is favored by cool, moist soil conditions (just what we had for many weeks in May). The soil temperature range for infection is 50°-75°F, with an optimum of 60°- 65°F. At soil temperatures above 78°F, the disease is greatly inhibited. Soil moisture conditions that are favorable for onion and garlic growth are also best for white rot development.
An increase of white rot in a field that has had several Allium crops may go unnoticed for a time as sclerotia numbers increase and disperse. One sclerotium per 20 pounds of soil will cause disease and results in measurable crop loss. The sclerotia will lay dormant until root exudates, exclusively from an Allium species, stimulate germination. Root exudates from non-Allium species will not stimulate the germination of white rot sclerotia. Cool weather is needed for both sclerotia germination and mycelia growth. Mycelia will grow through the soil until they encounter an Allium root at which time the fungus initiates infection. Mycelia can grow from one plant to a nearby plant, allowing the pathogen to move between plants.
Management of white rot should focus on disease avoidance by not introducing the pathogen into a field. Sclerotia can spread throughout a field, or from field to field, through the movement of soil, equipment, or plant material (especially garlic cloves). Sanitation is important to prevent sclerotia from moving from an infested field to a clean field. Plant only clean stock from known origins that has no history of white rot. Always clean soil off of equipment and sanitize with quaternary ammonia before moving to another field. The Allium crops from an infested field should not be used as seed. Rotation alone will not control white rot because sclerotia can survive in the soil for 20-40 years. If the disease is found, reducing or eliminating irrigation will reduce the damage to the current crop but will not stop the spread of the disease.
Because the fungus is vulnerable to temperatures above 115°F, dipping seed garlic in hot water is a possible preventive measure that will reduce the amount of pathogen but will not completely eliminate it. Temperature control is important when using this method because temperatures above 120°F may kill the garlic. There are other cultural and organic practices that a grower might try to fight this disease and these can be found at: https://rvpadmin.cce.cornell.edu/uploads/doc_479.pdf
Chemical applications can be made for white rot management and include for onion tebuconazole applied in a 4-6 inch band over or into the furrow at planting or via chemigation. For garlic an in-furrow at-planting application using iprodione or tebuconazole or fludioxonil can reduce disease incidence, however there are crop rotation restrictions with the use of these chemicals so be sure to check the Mid-Atlantic Commercial Production Recommendations guide for more details.
Broad Mites Found in Maryland Caneberries
By Jerry Brust Extension IPM Vegetable Specialist
University of Maryland [email protected]
About two weeks ago I heard some reports of possible damage caused by broad mites Polyphagotarsonemus latus in caneberries in the mid-Atlantic region. So I ventured out and looked at several raspberry and blackberry growing operations in Maryland. I found one farm with a light to moderate infestation of broad mites in their raspberries. This operation was relatively small consisting of a little more than a ¼ acre or so of caneberries. The problem with knowing whether or not you have broad mites is that the mites are so small, they are very difficult to find even with a 10x hand lens and their feeding can look very similar to the damage caused by some environmental problems or by viruses (which are usually the cause of the damage symptoms). Damage by broad mites usually consists of a distortion of young leaves (fig. 1) or flower buds as the mites show a preference for young, developing plant tissue. This feeding preference will result in the lower leaves of the plant remaining unaffected while the younger leaves are damaged.
Mites feed on the underside of foliage near the leaf stalk. This feeding often causes the growing tips to become misshapen with distorted leaves that curl up and have irregular brown discoloration. An infestation of mites can result in brown stripes that form on the leaves (fig. 2). A more serious infestation causes a total loss of green tissue, with the veins remaining green on a brown background. On the leaf stalks brown, corky patches can appear. What exactly causes the leaf tissue distortion and browning is not known, although it is thought that the mites release enzymes and other substances when they feed that disrupt localized plant growth. These distortions remain for weeks even after the mites have been eliminated and is the reason why extensive damage can be caused by a relatively low population of mites. Flowers that are fed upon will become discolored and deformed while fruit will develop corky areas and also become deformed.
Fig. 2 Sclerotia of white rot fungus on garlic.
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When I look for broad mites I look for their eggs which are very distinctive, relatively large and are not moving around as adults and immatures are. The eggs are clear with a symmetrical pattern of white dots on their surface (fig. 3). Even with a 20X hand lens it is still difficult to find the mites as they are often wedged down into folded or curled plant tissue. It really is important though to verify their presence as there are other causes of similar looking symptoms on raspberries and blackberries as I have learned.
When mite numbers reach 5 mites per leaflet (granted it will be difficult to see) or leaf deformities are found then treatments should begin. Horticultural oils are recommended when temperatures are below 88o F. Using the oils at temperatures above this may cause phytotoxic problems. Agri-Mek with a NIS has been found to be an effective product to control the motile stages of broad mites but it does not control the eggs so you’ll need to make two applications 7-days apart. There are other miticides that are available and can be used, but the key to any of them and the oils is to get good coverage of the curled and distorted plant tissue especially the underside of the leaf.
Tomato Spotted Wilt Virus In Tomatoes
By Jerry Brust Extension IPM Vegetable Specialist
University of Maryland [email protected]
A couple of high tunnels and even a field of tomatoes have been found with tomato spotted wilt virus in Maryland. The high tunnel finds were not too suprising but the field was a bit as we usually do not see field infections until later in the season.
Tomato spotted wilt virus (TSWV) is an obligate parasite, i.e., it must have a living host and must be moved from one plant to another by thrips or through cuttings or possibly seed. This disease can affect tomato and other Solanaceae crops as well as lettuce, beans, cucumber and 170 other plant species. TSWV may occur in the field but tends to affect greenhouse and high tunnel crops more severely. TSWV is transmitted most efficiently by Western flower thrips (WFT) (Frankliniella occidentalis), and less so by Onion thrips (Thrips tabaci), Tobacco thrips (Frankliniella fusca) and several other thrips species. It is not transmitted by Eastern flower thrips (Frankliniella tritici).
Western flower thrips completes its life cycle in about 10-18 days. Eggs are laid in the leaf or tomato fruit. When WFT oviposit into tomato fruit they often cause a deeper dimple (fig. 1) than other thrips species and very often the
dimple is surrounded by a white halo of tomato
tissue. Larvae hatch in about three days and immediately begin to feed and in so doing pick up the virus. After four days, they pupate in the soil, and in a little over three days, the pupae become adults. Only immature thrips can acquire the virus, which they can acquire within 15 minutes of feeding, but adults are just about the only stage able to transmit the virus. Adults can transmit the virus for weeks. It may take 2 - 4 weeks from when the adult thrips first fed on a plant to initial symptom occurrence. Because of this TSWV appears to worsen in plantings over time.
TSWV infected leaves may show small, dark-brown spots or streaks (fig. 2) on stems and leaf petioles (we found one weed sample with such a symptom). Growing tips are usually affected with systemic necrosis and potentially stunted growth. Tomato fruit will have mottled, light green or yellow spots or rings usually with raised centers (fig 3).
Fig. 2 Moderate to heavy broad mite feeding damage to raspberries.
Fig. 3 Broad mite eggs with their distinctive white dots
Fig 1 Tomato fruit with WFT ovipostion marks.
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On-Line PDF Click Here
Fig. 3 Tomato fruit with TSWV symptoms.
Fig. 1 Water soaked lesions on stems (red arrows) and tan lesions with necrotic areas on leaves (yellow arrows).
Fig. 2 Base of plant with tan lesions on stem with tiny black dots (pycnidia, blue circle) and brown and red ooze from an infected stem (red arrows).
Weed hosts act as important virus reservoirs for TSWV and can survive in and around greenhouses, high tunnels or fields. Some of these weeds include prickly lettuce, chickweed, spiny amaranth, lambsquarters, black nightshade, shepherd’s purse, galinsoga and burdock.
We tested for both INSV and TSWV on the tomatoes,
weeds and on any bedding plants that were in the same greenhouse as the tomatoes. Only TSWV was found in the tomato and some of the weeds. No INSV was found in any sample. Although both viruses are transmitted by the same thrips species these viruses tend to infect either bedding plants (INSV) or tomato/pepper plants (TSWV). The 2020-2021 Mid-Atlantic Commercial Vegetable Production Recommendations guide has recommendations for both greenhouse and field management of the thrips that vector TSWV. Never grow vegetable transplants in the same greenhouse with bedding plants.
Gummy Stem Blight In Cantaloupe
By Jerry Brust Extension IPM Vegetable Specialist
& Karen Rane
Plant Diagnostic Lab University of Maryland
Gummy stem blight (GSB) was found in an Eastern shore muskmelon field in the last few weeks. It is a cucurbit disease caused by the fungal pathogen Didymella bryoniae. This fungus is favored by cool to warm, rainy weather. It can infect a host at any stage of growth and affects almost all parts of the plant including leaves, stems and fruits. The earliest symptom of gummy stem blight is usually an odd-shaped lesion on the leaf (fig. 1). Often, these lesions are first observed on the vines or on leaf parts that are shaded or that collect moisture for long periods. Lesions on muskmelon leaves are usually a light brown to tan (fig. 1), while lesions on watermelon leaves tend to be a darker brown.
Infected stems at first show water-soaked lesions (fig. 2) that later appear tan. Older stems, particularly of muskmelon, show pycnidia (tiny black dots) within the infected tissue (fig. 2). These stem lesions often exude a gummy, reddish-brown liquid (fig. 2).
Fig. 2 Tomato leaves with TSWV symptoms and a positive immunostrip (two black arrows; Agdia, Inc)
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Fig. 3 Wilted cantaloupe plant with tan GSB lesion at base of stem.
Gummy stem blight may become established in the transplant greenhouse from contaminated seed or transplants, or from poor sanitation. A short time after some of these transplants go to the field they can unexpectedly wilt and die (fig. 3).
Didymella bryoniae survives in seeds, on surrounding weeds, or on organic debris from previously infected cucurbits. Without a host, the pathogen is able to overwinter and survive for over a year as hardened masses of hyphae. The pathogen is moved from infected hosts to other plants via ascospores carried by the wind and by conidia that are spread by water splash. Temperature and moisture are both important for infection and symptom development, but moisture causing a leaf wetness of 1 to 10 hours has the greatest influence. The optimal temperature for the disease to establish itself in a plant varies; for watermelon and cucumber it is 75-77° F but for muskmelon it is only 65° F. The optimal temperature for muskmelon is thought to be lower because the plant’s resistance increases as temperatures increase. Therefore, it is important to closely watch for GSB development in cooler weather in muskmelon. Physical wounding by mishandling or by striped cucumber beetle or aphid feeding can predispose plants to infection.
Best preventative chemical management includes: Chlorothalonil that is mixed with another product such as prothioconazole or tebuconazole. Another good option is mixing chlorothalonil with Luna Experience, which has tebuconazole and fluopyram. You also can check other spray options for muskmelon and other cucurbit crops in the Mid-Atlantic Commercial Vegetable Production Recommendations guide.
CDMS - Pesticide Labels and MSDS at:
http://www.cdms.net/
Avoiding Blossom End Rot By Gordon Johnson
Extension Vegetable & Fruit Specialist University of Delaware
Variable June weather often creates conditions favorable for blossom end rot in susceptible crops, with tomatoes and peppers being the most affected. In most years, there is a transition point in June where temperatures move from the moderate side to an extended hot period with temperatures in the 90s. This is also when many tomatoes and peppers have reached full plant size with high water demand and have large numbers of flowers and developing fruit with heavy calcium demand.
While field tomatoes are not near this stage yet, high tunnel tomatoes are susceptible. We are seeing days in the 90’s and high tunnel tomatoes will have high water demand.
Blossom End Rot (BER) is a disorder where developing fruits do not have enough calcium for cell walls, cells do not form properly, and the fruit tissue at the blossom end collapses, turning dark in color. Calcium moves through cation exchange with water movement in the fruit, so the end of the fruit will be the last to accumulate calcium. Larger fruits and longer fruits are most susceptible. With fruits, the rapid cell division phase occurs early in the development of the fruit and if calcium accumulation in the fruit is inadequate during this period, BER may occur. While it may not be noticed until the fruit expands, the deficiency has already occurred and cells have already been negatively affected. We most commonly see signs of blossom end rot on fruits two weeks after the calcium deficiency has occurred.
Understanding blossom end rot also requires an understanding of how calcium moves from the soil into and through the plant. Calcium moves from the soil exchange sites into soil water and to plant roots by diffusion and mass flow. At plant roots, the calcium moves into the xylem (water conducting vessels), mostly from the area right behind root tips. In the xylem, calcium moves with the transpirational flow, the movement of water from roots, up the xylem, and out the leave through stomata. Calcium is taken up by the plant as a divalent cation, which means it has a charge of +2. It is attracted to negatively charged areas on the wall of the xylem, and for calcium to move, it must be exchanged off the xylem wall by other positively charged cations such as magnesium (Mg++), potassium (K+), ammonium (NH4+), or additional calcium cations (Ca++). This cation exchange of calcium in the xylem requires continuous movement of water into and up through the plant. It also requires a continuous supply of calcium from the soil.
In general, most soils have sufficient calcium to support proper plant growth. While proper liming will ensure there is adequate calcium, it is not the lack of calcium in the soil that causes blossom end rot in most cases. It is the inadequate movement of calcium into plants that is the common culprit. Anything that impacts root activity or
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effectiveness will limit calcium uptake. This would include dry soils, saturated soils (low oxygen limits root function), compaction, root pathogens, or root insect damage. In hot weather on black plastic mulch, roots can also be affected by high bed temperatures. Low pH can also be a contributing factor. Calcium availability decreases as pH drops, and below a pH of 5.2 free aluminum is released, directly interfering with calcium uptake. Again, proper liming will ensure that this does not occur. Applying additional calcium as a soil amendment, above what is needed by normal liming, will not reduce blossom end rot.
In the plant, there is a “competition” for calcium by various plant parts that require calcium such as newly forming leaves and newly forming fruits. Those areas that transpire the most will receive more calcium. In general, fruits have much lower transpiration than leaves. In hot weather, transpiration increases through the leaves and fruits receive lower amounts of calcium. High humidity will reduce calcium movement into the fruit even more. Tissue tests will often show adequate levels of calcium in leaf samples; however, fruits may not be receiving adequate calcium. In addition, in hot weather, there is an increased risk of interruptions in water uptake, evidenced by plant wilting, when transpirational demand exceeds water uptake. When plants wilt, calcium uptake will be severely restricted.
Therefore, excess heat and interruptions in the supply of water (inadequate irrigation and/or rainfall) will have a large impact on the potential for blossom end rot to occur. Proper irrigation is therefore critical to manage blossom end rot.
As a positive cation, there is “competition” for uptake of calcium with other positive cations. Therefore, if potassium, ammonium, or magnesium levels are too high in relation to calcium, they can reduce calcium uptake. To manage this, do not over-fertilize with potassium or magnesium and replace ammonium or urea sources of nitrogen with nitrate sources.
Applying additional soluble calcium through irrigation, especially drip systems, can reduce blossom end rot to some degree if applied prior to and through heat events and if irrigation is applied evenly in adequate amounts. Foliar applications are only partially effective when applied to very young developing fruit. Fruits do not absorb much calcium, especially once a waxy layer has developed, and calcium will not move from leaves into the fruit (there is little or no phloem transport). Foliar applications of 2-4 lb Calcium (Ca) per acre is recommended. Foliar calcium can be applied as calcium chloride at the rate of 5-10 lb per 100 gallons per acre, calcium nitrate at the rate of 10-15 lb per 100 gallons per acre, or chelated calcium at labeled rate.
In conclusion, the keys to controlling blossom end rot are making sure roots are actively growing and root systems are not compromised, soil pH is in the proper range, and irrigation is supplied in an even manner so that calcium uptake is not interrupted. Supplemental calcium fertilization will only marginally reduce blossom end rot if water is not managed properly.
Understanding Effectiveness of Resistance Management Tactics: Towards a Better Stewardship of
Extant Fungicides By Mengjun Hu
Small Fruit Pathologist University of Maryland
Fungicides can be divided into two general groups: single-site fungicides and multi-site fungicides. Multi-sites such as Captan and Mancozeb usually attack multiple enzymes in a given fungus. In contrast, single-sites such as Abound and Indar are active against only one critical enzyme. While such enhanced specificity typically make single-sites more effective and less toxic, fungal pathogens can find ways more easily to overcome this chemical group. Once resistance is developed, it does not go away soon. FRAC codes on fungicide labels starting with ‘M’ indicate multi-sites, whereas only numbers are assigned to single-site fungicides.
A variety of resistance management tactics have been developed based on mathematical models, such as alternation, mixtures, timing adjustment, and increasing or splitting dose. Multi-year trials were usually conducted following the development to validate their usefulness. In this article, we will provide a brief review of principles of these tactics and their impact on resistance selection based on experimental evidence. Alternation: The fungicides are applied in alternation. This has been a common strategy for resistance management. The hypothesis is that the resistant strains are at a selective disadvantage (aka fitness cost) in periods when the target fungicide is not used, leading to a decrease in the fraction of the resistant population. However, IF resistant strains do not have fitness cost, it will take exactly the same number of sprays to build up a given level of resistance to that fungicide. In other words, this strategy may not be useful if fitness cost is not associated with resistant strains. Although efforts have been made to understand potential fitness cost in pathogens with resistance to multiple chemical classes of fungicides, results were inconclusive. However, resistance to benzimidazoles (FRAC 1) and strobilurins (FRAC 11) were found to be persistent in different fungal pathogens in the absence of fungicide pressure. Regardless, alternation may or may not be a good tactic, but it does not seem to increase resistance selection.
Mixtures: The fungicides are applied in mixture. A compensatory mechanism for failure of one component, which may have additional advantage over alternation: 1) Improved disease control (broader spectrum); 2) Disease
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control security when resistance is present; 3) Possible synergistic interaction between fungicides; 4) Fraction of fungal population with resistance typically remains low, regardless of fitness cost. In fact, many premixtures such as Pristine and Merivon have been developed by chemical companies, in light of improved resistance management. However, there are different mixing options, which could have differential effects on resistance selection under absence/presence of resistance scenarios.
1. Mixing a high or medium risk fungicide (single-site) with a low risk fungicide (most multi-sites are at low-risk for resistance development) a). resistance is absent: resistance can be managed with both fungicides b). resistance is present: resistance can be managed with the low-risk fungicide 2. Mixing two high or medium risk fungicides with different modes of actions a). resistance is absent: resistance can be managed with both fungicides b). single-resistance is present: resistance can be managed with one fungicide, but may not be sustainable. c). dual-resistance is present: increase resistance selection and fail in disease control 3. Mixing two low-risk fungicides: No change of risk to the use of either component used solo Taken together, #1 seems to be a wise option especially when resistance situation is largely unknown.
Dosage effect: high dose or low dose? This has been a debate, but it becomes clearer that high dose may increase resistance selection and low dose should be considered for better resistance management. A high rate of a fungicide may delay the emergence of resistance by reducing the size of the sensitive pathogen population and therefore the number of resistant mutants produced per unit time. However, the smaller pathogen population will reduce the competition between the sensitive and the resistant strain for healthy host tissue to infect and may therefore increase the probability that the resistant mutant invades the pathogen population. How low is considered “low dose”? Although there is no data, the dose needs to be effective against the disease, but preferably as low as possible. However, fungicides are frequently used during rainy days in the field. With more than one inch of rain, some protectant fungicides can be washed off by as much as 50%, further complicating rate use for resistance management. But most “to-be-protected fungicides” (e.g. single-sites) are more systemic than multi-sites, thus more resistant to wash-off by rain.
Experimental evidence: The table below summarized the published evidence of the effectiveness of fungicide resistance management tactics. As discussed above, alteration and mixtures are deemed to be good tactics in general, whereas increasing dose or spray numbers would increase selection for fungicide resistance. Please note that mixtures and alternation tactics have two types in the table. Studies included in type 1 examined the effectiveness using the full dose of the to-be-protected fungicide, whereas half dose was applied in type 2. Therefore, the dose of the to-be-protected fungicide was the same in the two compared treatments (single product vs alternation or mixtures) in type 1, whereas the total dose of the fungicide is not the same in type 2. Interestingly, alternation appeared to work only when the dose of the to-be-protected fungicide was reduced, further supporting the use of low-dose for resistance management.
In a nutshell: Resistance management is important to maintain efficacy of many commonly used single-site fungicides. When disease pressure is high during critical control window, perhaps using mixtures of a low-risk fungicide at high dose and a high-risk fungicide at low dose would be beneficial for both resistance and disease management. Keep in mind that resistance will not be selected if no sprays are made. The best resistance management strategies or fungicides are not as good as good weather conditions: spray as needed, and minimizing unnecessary sprays is key to managing resistance issues. References: Van den Bosch et al. 2014. Governing principles can guide resistance management tactics Annual Review Phytopathology. 52:175-195 Hobbelen et al. 2014. The Emergence of Resistance to Fungicides. PloS one. 9(3): e91910. Van den Bosch et al. 2011. The dose rate debate: does the risk of fungicide resistance increase or decrease with dose? Plant Pathology. 60:597-606
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Understanding Soil Nitrogen By Bryan Butler
Principal Agent, Agriculture Carroll County Office
As we move into the main part of the growing season often it is difficult to predict how much and when to apply additional Nitrogen to vegetable crops. Below is a quick refresher on where Nitrogen can go and factors that will influence what is available to the plants.
It's understood that not all of the nitrogen (N) that crop producers pay for will actually be available for plant uptake. Some of it will be lost through volatilization, denitrification, leaching or surface runoff and some may even be unavailable due to immobilization. The following is a breakdown of what can happen to nitrogen in the soil. These terms are commonly used, but many may still be wondering just what exactly do these words mean? • Mineralization is the process in which organic N-
containing compounds (like manure or compost) are broken down into nitrate by microbes and made available for plant uptake. Since mineralization is a microbial-mediated process, soil temperature, moisture, pH and aeration all affect the rate of process.
• Nitrogen fixation is a biological process in which elemental N is converted into organic N compounds through microorganisms in the soil. Organic N compounds are then converted into plant-available nitrate or ammonium through further microbial activity. Legumes (like clover, beans, or alfalfa) are responsible for most biological N fixation however, some fixation does occur by free-living organisms in the soil. Fertilizer application rates should be adjusted when legumes are used in crop rotations.
• Immobilization can occur when organic matter with high carbon to nitrogen ratios, such as wheat straw, sawdust, corn and grain sorghum decompose. Immobilization is generally a short term process in which the available nitrate-N in the soil is "tied-up" during decomposition. Crops planted during an immobilization period can show N deficiency if no supplemental N is supplied.
• Nitrate-N leaching can occur in areas where there are sandy soils. Leaching can happen when excess rainfall or irrigation water causes a rapid movement of the water below the root zone. Positively charged N that is in the form of the ammonium ion, however, doesn't leach since it is held in the soil by negatively charged clay particles and organic matter.
• Denitrification is a process by which nitrate or nitrite ions (except for ammonium-N) are broken down into gaseous forms of N by anaerobic organisms under waterlogged soil conditions. These gaseous forms are then lost to the atmosphere. For substantial losses to occur, however, soils usually have to be waterlogged for several days.
• Volatilization refers to the loss of N in the form of ammonia from the soil to the atmosphere and can occur when anhydrous ammonia is applied improperly. It can
also occur from manure or urea-containing fertilizers that are left on the surface of the soil. To minimize losses, producers can incorporate the manure or urea into the soil or apply it shortly before an expected rainfall. A rainfall of a half-inch or more will move urea into the soil.
A better understanding of who nitrogen acts in the soil helps all of us to use this very important nutrient to its maximum potential. This will be especially true this year with high nitrogen prices and as always to prevent losses to ground water.
Bifenthrin Receives 2020 Section 18 for Control of BMSB on Apples,
Peaches and Nectarines May 21, 2020
The registered products, Brigade WSB (10% bifenthrin, EPA Reg. No. 279-3108) manufactured by FMC Corporation; and Bifenture EC (25.1% bifenthrin, EPA Reg. No. 70506-57) and Bifenture 10DF (10% bifenthrin, EPA Reg. No. 70506-227), both manufactured by UPL NA Inc. may be applied. Applications must be made post-bloom, by ground only, at a rate of 0.08 to 0.2 lb. active ingredient bifenthrin (a.i.) per acre; no more than 0.5 lb. a.i. per acre may be applied per year; multiple applications may be made at a minimum of 30 day intervals; a restricted entry interval (REI) of 12 hours and pre-harvest interval (PHI) of 14 days must be observed.
All applicable directions, restrictions, and precautions on the EPA-registered product labels, as well as those outlined on the section 18 use directions referenced in your request, must be followed.
These exemptions expire October 15, 2020.
To help minimize exposure to pollinators, the following statement on the application timing must be observed: "Do not apply this product until after petal fall." To mitigate risks to aquatic organisms, section 3 product label requirements must be strictly followed. For ground applications (the only method allowed under this exemption) a 10 ft vegetative buffer strip, or a 25 ft buffer zone is required between the site of application and adjacent bodies of water. Recommendations on the section 3 product labels regarding droplet size, wind direction and speed, temperature inversions, and other factors affecting off-site drift or runoff of bifenthrin must also be carefully followed.
This is the ninth year that emergency exemption requests have been made for the uses of bifenthrin on apple, peach, and nectarine. An IR-4 petition to support a section 3 registration is currently undergoing review within EPA.
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Mastering Marketing – June 2020 Pivot to Bundling Products to Increase Sales ”Pivot to Bundling Products to Increase Sales” has been posted on the web. To access the article click on the link below:
Click Here
If you have any questions or comments about this article or have clients or colleagues that would value receiving it as well, please contact Ginger Myers at: [email protected] or [email protected]
FieldWatch offers three free voluntary mapping tools called DriftWatch, BeeCheck, and FieldCheck. All Maryland beekeepers, specialty crop growers, and pesticide applicators are encouraged to sign up.
To register, go to FieldWatch.com and choose the type of account you would like to create. Beekeepers should register for BeeCheck, specialty crop growers should register for DriftWatch, and applicators should register for FieldCheck.
For more information about FieldWatch, read this helpful resource or call the department’s Pesticide Regulation Section at 410-841-5710.
Timely Viticulture is an electronic newsletter that is designed to give those in the grape industry a timely reminder of things they should be considering in the vineyard. Since we are all busy it is not meant to be an exhaustive list of things to consider or even a full discussion of the options. It is just meant to think about what is happening and what is coming up, with some comments. To view Timely Viticulture Click Here
Post-Bloom (June) • Downy Mildew Management (pdf) • Minimizing Herbaceous Character in the
Vineyard (pdf) • Pre-Bloom to Post-Bloom Disease
Management (html) (pdf) • Red Leaves in the Vineyard—Diagnosis and
Management (html) (pdf) Mid-Season (June-July)
• Brown Marmorated Stink Bug (BMSB) - Part 1 (pdf)
• Brown Marmorated Stink Bug (BMSB) - Part 2 (pdf)
• Crop Estimation (html) (pdf) • Crop Management (html) (pdf) • Disease Management - Botrytis (html) (pdf) • Drought Stress, Vine Performance, and Grape
Quality (pdf) • Grape Berry Moth (html) (pdf) • Hail Damage (pdf) • Japanese Beetles (html) (pdf) • Mid-Season Disease Management (pdf) • Red Leaves in the Vineyard—Diagnosis and
Management (html) (pdf) • Spotted Lanternfly (SLF) I -
Background (html) (pdf) • Spotted Lanternfly (SLF) II - Scouting and
Management (html) (pdf) To subscribe to receive this publication, please contact Dr. Fiola at 301-432-2767 x344 or by email at: [email protected]
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EPA Offers Clarity to Farmers in Light
of Recent Court Vacatur of Dicamba Registrations
The U.S. Environmental Protection Agency (EPA) issued a key order providing farmers with needed clarity following the Ninth Circuit Court of Appeals’ June 3, 2020, vacatur of three dicamba registrations. Today’s cancellation order outlines limited and specific circumstances under which existing stocks of the three affected dicamba products can be used for a limited period of time. EPA’s order will advance protection of public health and the environment by ensuring use of existing stocks follows important application procedures.
“At the height of the growing season, the Court’s decision has threatened the livelihood of our nation’s farmers and the global food supply,” said EPA Administrator Andrew Wheeler. “Today’s cancellation and existing stocks order is consistent with EPA’s standard practice following registration invalidation, and is designed to advance compliance, ensure regulatory certainty, and to prevent the misuse of existing stocks.”
EPA’s order will mitigate some of the devastating economic consequences of the Court’s decision for growers, and particularly rural communities, at a time they are experiencing great stress due to the COVID-19 public health emergency. Details of the Order EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan. 1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant. 2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020. Background On June 3, 2020, the Ninth Circuit Court of Appeals issued an order vacating EPA’s pesticide registrations containing the active ingredient dicamba: Xtendimax with Vaporgrip Technology (EPA Reg. No. 524-617); Engenia – (EPA Reg. No. 7969-345); and FeXapan – (EPA Reg. No. 352-913).
Dicamba is a valuable pest control tool that farmers nationwide planned to use during the 2020 growing season. Since the Court issued its opinion, the agency has been overwhelmed with letters and calls from farmers citing the devastation of this decision on the millions of acres of crops, millions of dollars already invested by farmers, and threat to America’s food supply.
Paraquat Dichloride Training for Certified Applicators As required by EPA’s Paraquat Dichloride Human Health Mitigation Decision and amended paraquat dichloride (a.k.a. paraquat) product labels, certified applicators must successfully complete an EPA-approved training program before mixing, loading, and/or applying paraquat. The training provides important information about paraquat’s toxicity, new label requirements and restrictions, and the consequences of misuse.
The EPA-approved training module can be accessed here. This training was developed by paraquat manufacturers as part of EPA’s 2016 risk mitigation requirements and has been approved by EPA.
Department Confirms First Spotted Lanternfly Hatch of 2020
Marylanders Encouraged to Keep a Lookout for this Invasive Pest
The Maryland Department of Agriculture has confirmed the first spotted lanternfly hatch of 2020. The first instar nymph of the season was reported by a department employee while surveying for the pest in the upper northeast corner of Cecil County near the Pennsylvania border.
“Our department continues to work closely with our federal and state partners to survey and prepare for the emergence of this invasive pest in our state,” said Secretary Joe Bartenfelder. “As spotted lanternfly nymphs start to hatch, I encourage all Marylanders to keep a lookout for
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this insect that has the potential to devastate many of our farmers' crops.”
The spotted lanternfly poses a major threat to the region’s agricultural industries as it feeds on over 70 different types of plants and crops — including grapes, hops, apples, peaches, oak, pine, and many others. As a known hitchhiker, the spotted lanternfly has confirmed populations in neighboring states, Pennsylvania, Delaware, Virginia, West Virginia, and New Jersey. In Maryland, spotted lanternfly hatching has begun and will last through mid-July. Marylanders should stay vigilant for spotted lanternfly, which, in its current life stage, appear as tiny white-spotted angular black nymphs about a quarter-inch in size.
Following the department’s 2019 survey season, Maryland was found to have established populations of spotted lanternfly in Cecil and Harford counties. In fall of last year, the department’s Plant Protection and Weed Management Program partnered with the U.S. Department of Agriculture (USDA) to treat Ailanthus altissima, the spotted lanternfly’s preferred host, at multiple sites in Cecil and Harford counties. Treatment will begin again in late May or early June. The department’s Plant Protection and Weed Management Program continues to work with the USDA Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine (PPQ) program, University of Maryland Extension, and others to monitor for the insect in Maryland.
A quarantine zone has been in effect for Cecil and Harford counties since October 2019 in an effort to control the spread of this invasive insect to other parts of the state. All spotted lanternfly permits for Virginia, Pennsylvania, New Jersey, and Delaware are transferable and valid throughout the region — meaning a permit from any of these states can be used in Maryland.
Businesses that require the movement of any regulated item within or from the quarantine zone must have a permit. A Maryland permit can be obtained by taking a free online training course through PennState Extension. Upon completion of the course and an online exam, individuals will receive a permit. Managers, supervisors, or employees of businesses operating in the quarantine zone must receive the approved training and pass the exam by at least 70% to demonstrate a working knowledge and understanding of the pest and quarantine requirements. Training of other employees, inspection of vehicles and products, and removal of living stages of spotted lanternfly must also be completed.
Those living within the quarantine zone are encouraged to be vigilant in containing the spread of spotted lanternfly. The department has created a residential compliance checklist that is available for download on its website and will educate residents on the life cycle of the spotted lanternfly and areas to inspect around the home.
If you suspect you have found a spotted lanternfly or their egg masses, snap a picture of it and then smash it. Report the sighting with photo attachments and location
information to the Maryland Department of Agriculture at [email protected]. Dead samples of spotted lanternfly from any life stage can be sent to the Maryland Department of Agriculture’s Plant Protection and Weed Management Program at 50 Harry S. Truman Parkway, Annapolis, MD 21401.
Department Announces Dates for Pesticide Container
Recycling Program The Maryland Department of Agriculture’s Pesticide Regulation Section has announced 2020 dates and locations for its pesticide container recycling program. Each regional location will offer multiple recycling
dates from June through September. This free program allows farmers, certified applicators, and other pesticide users to recycle used plastic containers at no cost.
Maryland’s pesticide container recycling program is a partnership between federal, state and local agencies and private industries. The program is free and open to all agricultural producers and pesticide applicators. The Agricultural Container Recycling Council provides a chipper to grind the used plastic containers into flakes, which are then transported to a contractor for recycling. The containers collected in Maryland have yielded nearly 1 million tons of recyclable plastic flakes.
A schedule of collection dates and locations is available on the department’s website. All recycling events will be subject to requirements of emergency orders related to COVID-19. All patrons and staff should wear cloth face coverings and follow best practices established by the U.S. Centers for Disease Control and Prevention and the Maryland Department of Health.
For additional information, or to schedule a chipping date at your site, contact the department’s Pesticide Regulation Section at 410-841-5710.
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Follow Sonny Perdue and others on SoundCloud.
This month, Secretary Sonny interviews a farmer and a processor to talk about USDA’s Farmers to Families Food Box Program. The food supply chain as a whole has been hit hard by the coronavirus – from the farmers that grow the food, to the processors who
move the food, to the families who need food now more than ever. To work through these challenges, USDA created innovative new program, called Farmers to Families Food Box, where we buy excess produce, dairy and meat from our farmers and processing companies box it and deliver it to those most in need. Programs like this are the best that America has to offer – it all comes down to Americans helping Americans.
Coronavirus Food Assistance Program Are you a farmer or rancher whose operation has been directly impacted by the coronavirus pandemic? The Coronavirus Food Assistance Program provides direct relief to producers who faced price declines and additional marketing costs due to COVID-19. Farm Service Agency (FSA) is now accepting applications for the Coronavirus Food Assistance Program (CFAP). The program will assist, with direct payments, to grain, livestock, dairy, and specialty crop operations that have suffered sales declines and increased marketing costs due to the pandemic. Signup began last Tuesday, May 26th and runs through August 28th. Attached are fact sheets on the particulars of each program section. To learn more one can go to www.farmers.gov/cfap or simply call an FSA office. Note: FSA offices are currently closed to the public, but we are able to take applications over the phone and through email. Application submissions can be submitted through mail, email, or dropping off materials at a drop box outside the service center doors.
See the latest Food Safety Newsletter CLICK HERE
Register Today for Produce Safety Rule “How-To” Webinars
In the past few years, many produce growers in our region have attended a mandatory full-day training class to learn about the requirements of the Produce Safety Rule (PSR). According to state Departments of Agriculture, however, there are common reasons why farms, despite best efforts, are not noncompliant with the PSR. In an effort to help farmers achieve compliance, the Maryland Food Safety Network has created a monthly webinar series on how to remedy common areas of PSR non-compliance. The series, titled “Food Safety Fridays- a ‘How-to’ Webinar Series” will be held one Friday each month from May to November. The next webinar on June 19, 2020, at noon, will focus on conducting water risk assessments. Register here: https://foodsafetyfridays.eventbrite.com.
To make a complete “PSR compliant” water risk assessment, growers are required to perform and document an annual inspection of their farm’s water distribution system from “source to spigot.” According to Molly Gillingham at the Maryland Department of Agriculture, “by conducting on-farm readiness reviews we work with growers to identify areas of their farm that need to be strengthened in order to comply with the PSR. An annual water distribution inspection is something that has consistently been found lacking on many Maryland farms. In order to comply, growers need to understand what needs to be included in this type of assessment and how to properly document the inspection.” This type of practical information will be provided in the webinar on June 19th.
This webinar series is recommended for operators who have attended a Produce Safety Rule Grower Training and want more information on how to apply what they learned and what records they need to keep to be in compliance with the PSR. Because the PSR is based in federal law and establishes national standards, growers from outside of
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Maryland are welcome to attend and will benefit from tuning in.
The series kicked off on May 22, 2020 with a webinar on how to effectively and efficiently train your workers, which was recorded and is available to watch on the Maryland Food Safety Network Platforms, including http://umaglaw.org/about/food-safety/ and https://extension.umd.edu/foodsafety. The other webinars in the series will be as follows: June 19, 2020, How to: Make Water Risk Assessments - Learn how to inspect your water distribution system and conduct a water risk assessment. July 17, 2020, How to: Get a Handle On Water Quality - Learn how to properly test your water, communicate with the water testing lab, and how to interpret water test results. August 21, 2020, How to: Manage Wildlife - Learn how to conduct pre-harvest assessments for wildlife and how to create appropriate buffer zones for contaminated produce. September 18, 2020, How to: Develop a Sanitation Program-Learn how to identify equipment requiring cleaning and sanitizing (including transportation equipment) and create and implement cleaning and sanitizing schedules. October 16, 2020, How to: Apply, Handle and Store Biological Soil Amendments - Learn how to determine if your soil amendment is treated or untreated, establish composting protocols, and safely apply and manage untreated amendments on the farm. November 20, 2020, How to: Put It All Together in a Food Safety Plan - Learn how to structure what you have learned throughout the webinar series into a customized food safety plan for your farm. Register for the webinars today at: https://foodsafetyfridays.eventbrite.com! Registration for each webinar is required. Anyone with questions can contact Sarah Everhart, 410-458-2475. Funding for this series of webinars was made possible, in part, by the Food and Drug Administration through grant PAR-16-137. The views expressed in written materials or publications and by speakers and moderators do not necessarily reflect the official policies of the Department of Health & Human Services; nor does any mention of trade names, commercial practices, or organization imply endorsement by the United States Government.
Are Bears Coming to Your County?
The recording of our Woodland Wildlife Wednesday webinar on May 27th is now available through our website's "Webinar Recordings" library.
Biology, Management, & Behavior of Black Bears in Maryland (60 minutes) Presented by the Woodland Stewardship Education program of the University of Maryland Extension.
Speaker: Harry Spiker, Black Bear Biologist, Maryland Dept. of Natural Resources - Wildlife & Heritage
Our next webinar is scheduled for June 24th. More details and how to register will be available later this month.
Thank you for your interest in our webinar series. On the web at extension.umd.edu/woodland On Facebook at www.facebook.com/UMDWSE On YouTube at www.youtube.com/user/UMdFSE Andrew A. Kling Agent Associate, Woodland Stewardship Education program University of Maryland Extension Western Maryland Research & Education Center 18330 Keedysville Road, Keedysville MD 21756
**UPDATED** See new information, services, and assistance regarding COVID-19 CLICK HERE
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Crop Talk Starting June 19th, at Noon To Register for Crop Talk Click Here
OUR AGRONOMY AND HORTICULTURE EXPERTS ARE
HERE TO HELP
For well over 100 years, University of Maryland Extension has fulfilled its mission of delivering science-based education to Maryland communities. We will not waiver on that promise. Our educators and faculty members are quickly developing new learning opportunities to continue to meet the needs of our customers and are working to ensure you have the science-based information you need to protect people and reinvigorate businesses threatened by COVID-19. We are ready to serve you.
While our offices are closed, we are still working to provide assistance.
• Call or email us: We continue to answer questions and conduct field research to deliver the resources you need.
• Field visits: If needed and following social distancing protocol, we continue to conduct on-site field visits for diagnosis of production issues.
University of Maryland Extension Online Resources at: https://extension.umd.edu/
Remember the Quarantine
Spotted Lanternfly Permit Training: Click Here
Vegetable & Fruit News A timely publication for the commercial vegetable and fruit industry available electronically in 2020 from April through October on the following dates: April 16, May 14, June 11, July 9, August 13, September 10 and October 29 (Special Research & Meeting Edition). Published by the University of Maryland Extension Focus Teams: 1) Agriculture and Food Systems; and 2) Environment and Natural Resources. Submit Articles to: Editor, R. David Myers, Extension Educator Agriculture and Natural Resources 97 Dairy Lane Gambrills, MD 21054 410 222-3906 [email protected] Article submission deadlines for 2020 at 4:30 p.m. on: April 15, May 13, June 10, July 8, August 12, September 9 and October 28 (Special Research & Meeting Edition). Note: Registered Trade Mark® Products, Manufacturers, or Companies mentioned within this newsletter are not to be considered as sole endorsements. The information has been provided for educational purposes only. The University of Maryland Extension programs are open to any person and will not discriminate against anyone because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, national origin, marital status, genetic information, political affiliation, and gender identity or expression.
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