INSTITUTE OF FOOC AND AGRICULTURAL SCIENCES

UNIVERSITY OF FLORIDA

FLORIDA COOPERATIVE

EXTENSION SERVICE

VEGETARIAN A Ve8etable Crops Extension Publication \.~gelable Crops Department• 1255 HSPP • Gainesville. FL 3'2f:>11 • Telephone 392-2134

Vegetari an 87- 11 November 16, 1987

Contents

I. NOTES OF I NTEREST

A. Vegetable Crops Calendar .

B. New Publications .

II . PESTICIDE UPDATE

A. Section 18 for the Use of Fusilade on Celery and Head Lettuce .

B. Nightshade Control Reduction With Paraquat Due to Copper Fungicide Antagonism .

I II. COMMERCIAL VEGETABLES

A. 1987 Leek Variety Trial Res ults.

B. Use of Tensio meters in Vegetable Production.

IV . VEGETABLE GARDENING

A. Miniature Pumpkins .

Note : Anyone is fre e to use the information in this newsletter . Whenever possible , please give credit to the au thors.

The use of trade name s in t his publication is solely for the purpose of providing inf orma tio n and does not ne cessa rily constitu t e a recommendation of th e product.

The Instit ut e of Food and Ag ri/:ul tural Sciences is an Equal Employment Opportunity· A ffirmative Act io n Emp !oyer aut hori zed to provide research, educationa l informat ion and other serv ices on ly to indi viduals and inst i tutions that fu nct ion without regard to race, color, sex , or natio nal origin.

COOPERATIVE EXTE NSI ON WORK IN AGRICULTURE AND HOME ECONOMICS , STATE OF FLORI DA, IFA S, UNI VERSITY OF FLOR IDA, U.S . DEPARTMENT OF AGRICU LTURE , AND BOARDS OF COUNTY COMM ISSI ONERS COOPERATING

I. NOTES OF INTERESTS

A. Vegetable Crops Calendar

November 3-5, 1987 . FSHS Convention . Orlando Hyatt Hotel .

November 6, 1987 . ASHS Tours . Or ­lando Hya tt Hotel .

November 8-1 2, 1987 . ASHS Convention . Orlando Hyatt Hote l.

November 19 , 1987 . 9:00 am - 3 :3 0 pm Tenth Annual Conference for Vegetable Technical and Sales Reps . Kendrick Auditorium, Manatee Co. Ext. Office, 1303 17 Street, Palmetto . (Contac t Phyllis Gi lr eath - (813) 722-4524.)

November 30 - December 2, 1987 . USDA Vegetable Collaborators ' Conference . Omni Hot el , Charleston, SC (Contact Gary Elmstrom . )

December 7-11, 1987. Depa rtme ntal Review . ~lorida. Gainesville .

Vegetable Crops Univers ity of

B. New Pub l ications .

Tomato Variety Trial Results for Spring 1987 . Bradenton GCREC Re­search Rep t. BRA1987-20 by T . K. Howe , J.W . Scott , and W. E . Wat ers .

Recent Advances in Managing the Sweetpotato Whitefly on Poinsettia . BRA 1987-21, by J . F . Price, o . J . Schuster and D. E . Short .

Cucurbit Variety Evaluation, 1987 . Leesburg CFREC Research Rept . LBG 87-4 by G.W. Elmstrom .

To request the pub li cations , please contact authors directly .

- .i:.-

II . PESTICIDE UPDATE

A. Sect i on 18 for the Use of Fusi la de on Celery and Head Lettuce .

The Environmental Pr otec ti on Agency (EP A) has granted a Section 18 specific exemption to the Florida Department of Agriculture and Consumer Ser vices for the use of fluazifop - p-butyl (Fusilade 2000 ) on celery and head lettuce to control emerged goosegrass , crabgrass, bermu­dag r ass, foxtails, panicums, and barnyardgrass .

A maximum of 2 ground app l ica ­tions at a maximum rate of O . 188 lb a i /A may be made to celery .

A s ing le ground application of 0 . 18 8 lb ai/A may be made to head lett uc e .

Appl i cations will not be made within 30 days of har vest . Field flooding may not be made 45 - 60 days after last application. The exemp­tion expires July 31 , 1988. Read and follow all label directions and restriction s .

(Stall: Vegetarian 87-11)

Nightshade Control Reduction With Paraquat Due to Copper Fungicide Antagonism .

For severa l years , growers in the southwest Florida production area have reported what they believed to be the development of resistance to paraquat by nightshade plants . Di­rected, shielded paraquat applica­tions did not fully control the nigh tsh ade . Those that were not controlled were primarily found along the edge of the plastic mulch. It was first thought that these night ­shade plants ha d not been sprayed or that the co verage of paraquat that they recieved was lower than what was delivered to the midd l es due to nozzle ar ran gements. Whe n these plan ts were covered with a full rate of pa raquat hy hand held backpack

sprayers , they were not fully con ­trolled .

At the Gulf Coast Research and Education Cente r, Bradento n, Dr . Jim Gilreath found that paraquat stil l control l ed nigh t shade in his experi­ments .

While wondering if t here was truly a resistance established in the southwest Florida area , we observed that the weeds along t he sides of the beds were being covered wi th fungi­cides , and the copper in the mix was building up on the pl ant leaves .

Reggie Brown, Collier c,;ounty Extension Director harvested two large batches of nightshade berries from old fields . We extracted the seed from these fruit and grew several batches of plants ou t in Gainesville to try to determine if the copper fungicides was inhib i ting action of the paraquat .

In the experiments we divided the plan t s a nd sp r ayed no copper fung i cides , copper fungicides 3 times in 1 week and 6 times in 2 weeks on the nightshade pl ants . These p l ants were divided and paraquat was sprayed at 1/2 rate and full rate on each of the copper treatments .

The r esults were when no coppe r was sprayed on the nightshade plants, both the 1/2 and full rate of para­quat killed the plants . When 1 week of copper was sprayed on the plants, the stems collapsed in the upper portion of the plants , but resprout ­ed . Regrowth from the plants treated for 2 weeks with copper was prim~rily new leaf formation . very little stem kill was seen .

This exper i ment shows a definite antagonism between paraquat and copper fungicides when sprayed on the nightshade plants . The more copper on the plants , the less control obtained from paraquat .

We have also noted that younger nightshade plants are controlled to a greater extent than older plants, even with copper sprays .

- 3-

The experiments are still on ­going to find a mechanism to overcome the antagonism .

(Stall : Vegetarian 87 - 11)

III . COMMERCIAL VEGETABLES

A. 1987 Leek Variety Trial Results .

Commercial production of leeks (Allium ampeloprasum , Porrum Group) is s mall in Flo r ida at the present time . However, it appears that there is potential for more production based on comsumer interest . The Packer ' s recent profile of fresh produce consumers showed that of 30 spec i alty crops , 38% of the respon­dents had t r ied leeks , and another 48% indicated that they had heard of them .

Leeks are considered a major vege t ab l e crop i n Europe rather than a specialty crop as they are in the United States . For example , the leek crop in the United Kingdom in 1985 was about 50,000 tons and had an approximate value exceeding $26 mill i on .

Leeks , a long - season crop , are grown for their swollen, but not bulbed , leaf base , the edib l e portion is the shank whick extends from the stem plate to the base of the first aerial leaf . A white shank is requ i red for the market so blanching with soil or straw, for polyethylene­mnl chP-cl crops, i s required . Because of the necessity of blanching, the crop is p r obably better suited to open - ground cu lt ure than to mulched culture . Leeks are not as pungent as onions, and are prized for the i r delicate flavor . The crop can be dir e ct-seeded, but stand estab l ish ­ment from transplan t s is probably more desi r able . Leeks are very cold tolerant and a succession of plant ­ings should provide a continuous supply from la t e fall through mid­spring i n Central Florida .

Le ek yi e lds ranged f rom 3,391 lb for 'C ar ina' to 5,57 1 l b for ' Varna' per 1000 lb f . Yi e lds o f ' Kaza n ', '8240', ' Alba na', ' Kil ima', and ' Otina' were not sta ti st ica lly di f­fere n t f ro m those of ' Va rn a ', t he highest y ie lding va riet y . All of the othe r varieties produced yields th a t were not s ignif ic an tly different from ' Carina' th e lowest yielding var ie t y .

Weight of individual leeks ranged fr om 9 .4 oz for 'Car i n a ' to 14 .9 oz f or ' Varna'. Since th e r e was no di ffe re nce among the va ri e ties i n plan t sta nd, to t al yield was rel ated d i rectly t o individual plan t wei ght.

Plant height, measure d f r om the stem plate to the t i p of the longest leaf , ranged from 33.9 in . for ' Ele ctra' t o 52 . 3 in . for 'Varna '.

Shank leng t h is one of the most i mpo rt ant characteristics in le eks. ' Var na' pr odu ce d 10.5 i n . l ong shanks , whi ch may be too long for many mark ets . The shortest s ha nks were produ ce d by 'Conquero r' at 3 . 2 inches . Most varieties prod uced shanks that were i n the highly acceptab l e r ange of 3 . 5 to 6 in . long . Sh an k diameter did not vary grea t ly among the v arie tie s , and ranged f ro m 1.0 to 1. 5 i n . Most vari eties had 1 . 2 to 1. 4 in . diam et e r shanks . As would be exp ecte d fr om the fo reg oing , ' Varna ' had the highest shank length :d iameter ratio .

Leek leav es typically have an equ it ant arrangement , i . e ., leaves are overlapp in g in two ranks . When ful ly expressed , the leaves wil l be flat in a fa n- like arrangem ent . This should be consid ered an advantage t o facilitate bunch i ng . Some var ietie s in th is trial devi ated from the full y equitant arrangement: ' Varna', 'Kazan ' , ' 8240 ', ' Ot ina', 'Ar ge nta', 'Electra ', ' Ca tal ina ', 'Arm or', an d ' Carina ' were medium fla t whe re as 'Varina' and 'Conq ue r o r' were thick flat .

Observa tions we r e ma d e on t he tendency of t he se va ri etie s to bul b . Any deviation fro m a parallel shank was noted , ho wev e r s ligh t. Only

- q -

'Kilima' showed a mar ked tendency to bul b; it is un cert ain if this would have affe ct ed marketability of t he leek s.

Leeks are a lo ng season c r op . In thi s tria l , 70 days were required f r om seeding to transplant and 112 days ela ps ed between tra ns plan ti ng and initial harvest . Production t ime wou ld likely be somew hat shorte r for spring and fa ll crops . Th e yield po tenti a l for leeks wi t h two rows per bed on 4 . 5 ft . cen t ers i s high -53 ,927 lb f o r 9680 lbf .

See GCREC Res. Rept. BRA1987-1 7 for a complete re po r t of tria ls.

the se

(Maynard: Vegetarian 87-11)

B. Use of Tensiomet er s in Vege­table Pr oductio n .

Effic i ent irri gat ion practices are very imp ort ant in reducing farming costs and conse r vi ng natural resources . To be efficie nt i rrig a­tion managers , we must be ab le to predict water needs of our crops , and then appl y the water in measured fas hio n . One tool, mentioned in the October Guidelines, for i r riga t ion scheduling is t he tensiometer .

The t ensiometer is a simple inst r ument that indi rectly measures the amoun t of wat er in the so il . The instrument consists of a por ou s , ceramic cup connect ed to a va c uum gaug e through a long , rigid tu be (Fig11r.P. 1) . Av;dlable at most i rriga­tion supply companies, the tensiomet­e r cost s ab out $3 0 to $40 depending on length ne eded .

Installation . Before placing in the field, t he tensiometer must be readied by fi lling t he t ube with water an d a llow ing it to stand vertically in a buck et of wat e r to soak the cer ami c tip . A hand vacuum pump sh ould then be used t o r emove a ir bubb le s from the tensiometer gaug e. The pump , pu rc hased with the tensiometer, is placed over the open end of t he tensiometer tube and t he

air bubbles are pumped out . After pumping, top-off the water in the tube and replace the cap.

Choose a site in the field that is representative of that field or is representative of the irrigation management unit or zone. Avoid wet or dry areas . Place the tensiometers within the plant canopy in such· a manner that it is not shielded from rain or irrigation, nor is it subject to puddling .

Depth of placement is important . Place the tensiometer in the field so that the ceramic cup is in the zone of active roots . For many shallow­rooted vegetables , only one tensio­me te r with the ceramic cup in the 6 to 12-inch depth is needed . For moderately deep roots , two tensiomet ­ers may be needed at each site, one tensiometer placed deeper than the other .

Use a tensiometer soil coring instrument to create a cylindrical hole in which to place the tensiomet­er. Push the tensiometer into the hole to the correct depth , and lightly tamp the surface so i l to seal the instrument . A short period wil l be required for the correct reading to be established.

How it works . The tensiometer measures " soil moisture tension" . As the soil dries out, water is pulled from the tube through the ceramic tip . This creates a tension or vacuum inside the tube which is measured by the vacuum gauge . Afte r a rain or irrigation , water from the soil moves into the tube ceducing the vacuum . If the soil becomes too dry, air can move into the system and the instrument will not function .

The units of measurement and the gauge are called centibars and are a measurement of soi l moisture tension . Since we are really measuring a vacuum, the units are really negative but the minus sign is usually omi t ted on the gauge .

Irrigation sched uling . Tensio­meters help dec i de when to irrigate , but they do not tell how much water

- 5-

to apply . Depending on your soil type , different readings will indi ­cate when to irrigate . For sandy soils in Fl orida , this critical value is in the range of 12 t o 20 centibars but on heavier soils the critical value might be 60.

To determine the amount of water to apply, a moisture characteristic curve for your soil type must be used . Your extension agen t or farm advisor can help with this pr ob l em. The soil moisture curve will help tell you how much water needs to be applied to r eturn the tensiometer to the optimum read i ng for your soil and crop .

If you have the needed infor ­mation as described above, the tens­iome t er can be used to automate irrigations . The vacuum gauge can be fitted with a switch so that the irrigation system can be turned on and off to pre-set gauge readings.

Tens i ometer service. Periodic field service will be needed to keep the tensiometer operating properly. This is usually because of air being trapped in the tube . The tube should be checked regularly for air and topped off with more water if more than one - half inch of air accumu ­lates . In dry soils, this might be a weekly operat i on .

Tensiometers are fragile instru ­ments and should be handled with care. Be sure not to leave filled with water under freezing conditions .

Summary . Tensiometers can be a useful tool with which to schedule irrigations, especially when the system can be automated . Their proper use involves a little initial work to determine the moisture characteristic curve , but there are spec i alists that can help with this. With proper installation and mainte ­nance, they will continuously measure water potential and help you become an efficient i rrigation manager.

Reference

Smajst rla, A. G., o . s . Harrison , and F . X. Duran . 1985. Tensiometers for soil moisture measurement and irriga ­tion scheduling. Univ. Fla . Coop. Ext. Circ . 487 .

(Hochmuth: Vegetarian 87- 11)

IV . VEGETABLE GARDENING

A. Miniature Pumpkins .

Miniature vegetables of all types have been getting more and more popular with both gardeners and consumers over t he past few years . One that has become very prominent, e s pecially around Halloween and Thanksgiv in g, is the miniature pumpkin (mini-pumpkin).

This small, round, flat, orange pumpkin resembles its larg er rela ­tive , the Jack-0 - Lantern pumpkin , but is much smaller , seldom rea ch ing more than 6 ounces in weight , 3 to 4 inches in diameter. and 2 to 1 inches in height.

Some so-called mini-pumpkins are actually baby-sized regular pumpkins . For example, one named 'Little Lan ­tern' weighs 1 .9 lbs. and measures 5 inches wide by 4 inches high (Stokes Seed Company) , and another na med 'Baby Pam ' is 5 1/2 inches across (Gurney Seed Company) .

While there may be several more varieties of the mini - type, a few of today's more common ones are : 'Munch­kin ', a 3-4 inch diameter version sold by Moran Seed Company; 'Sweetie ­Pie ' , measuring 3 inches wid e , 1 3/4 inches high , and 5 ounces (Stokes Seed Company) ; 'Bushkin', once sold by Burpee Seed Company but recently removed from sales for further selec ­tion work; ' Jack-Be-Litt l e' , by Parks Seed Company, advertised as 2 inches high and 3 inches in diameter; and 'Mini-Jack ' , offered by Gur ney Seed Company .

Two common questions are fre­quently asked by gardeners and co n-

-6 -

sumers alike ; what k i nd of vegetabl e are these newcomers, pumpkins, gourds or what, and are they edible?

Well , the little orange fruits sure do look like pumpk i ns , but they are hard and not ve ry palatable, resembling the gaily-colo r ed orna­mental apple and pear gourds . Both regular jack - a - lantern type pumpkins and the ornamental gourds belong to the same genus and species , Cucurbita pepo. One is called a pumpkin because ~its soft tender edible flesh, while the other is called a gourd because it becomes hardened rather quickly and is generally considered to be inedible . Okay , so now we have the mini-pumpkins, which belong to this same species, which are soft at firs t but which become hard and unpalatable r ather quickly . Still they are true pumpkins, but have the most value as an ornamental gourd . Let's just call them ornamental mini ­pumpkins .

They grow on a rather short trailing vine, where they are quite prolific under Florida conditions. Unli k e regular pumpkins which produce only a few fruits per plant , there may be a dozen or more mini-pumpkins on the vine . Of course, since these cross readily with other Cucurbita pepo members, it is not uncommon to f ind a va ri ety of off - type fruits in the planting.

While the mini-pumpkin could be eaten safely when still immature (non - hardened) , by t he time most consumers purchase them, the fruits are already too tough and hardened to be palatable . For decorative effect, pain ted or plain, the 1 ittle mini­pumpkin appears to be around for a long time helping us enjoy Halloween and Thanksgiving even more.

(Stephens: Vegetarian 87-11)

-7-

Prepared by Extension Vege table Crops Specia l ists

Dr . D. J . Cant l iffe Chai r man

Dr . G. J . Hochmuth Asst . Professor

Dr . W. M. Sta l l Professor

Dr . D. D. Gull Assoc . Professor

Dr . D. N. Maynard Professo r