26

Refined Management of Lygus Bugs in Baby Lima Beans Larry Godfrey

1, Rachael Long

2, Steve Temple

3, Evan Goldman

1, and Mohammad-Amir Aghaee

1

ABSTRACT

The western tarnished plant bug, Lygus hesperus, is one of the most challenging pests to manage

in California’s agroecosystem and production of several types of beans are affected by this pest.

Bean yield and bean quality can both be severely impacted. Studies in 2011 were designed to

develop improved management options for this pest on baby lima beans in central California. In

summary, experimental insecticides were evaluated against this pest in small plots and two

materials were found to be very effective. These results support those from 2010. Rimon®, a

recently registered product was tested in grower fields and found to be an effective insect growth

regulator that will help suppress lygus nymphs in lima bean production. However, since Rimon

does not control adult lygus, it must be tank mixed with another insecticide that has efficacy on

adult lygus bugs, which may not be economical in dry bean production. ‘Haskell’, a vine baby

lima variety with a level of resistance to lygus bugs, was grown with various insecticide regimes

intended to supplement the level of pest control under high lygus pressure. The variety

performed well but the lygus bug pressure in 2011 was not high enough or occurring early

enough in the season to stress the variety and to fully fulfill this objective. Finally, procedures

were developed to aid in sampling lygus bug populations in vine baby lima beans with the goal

of making treatment decisions. The dense crop canopy of the vine beans inhibits the

effectiveness of the sweep net as a sampling tool. However, by adding a “correction factor”, i.e.,

doubling the number of lygus captured with the sweep net in vine beans, this tool can be used in

pest management and the results are comparable to those from bush beans.

Key Words: pest management, lygus bugs, chemical control, host plant resistance

INTRODUCTION

The western tarnished plant bug, Lygus hesperus, is one of the most challenging pests to manage in

California’s agroecosystem. Several factors contribute to the severe pest status including 1.) wide

host range of more than 200 plants, 2.) high mobility being able to move (fly) several miles, 3.)

readily develops resistance to insecticides, 4.) inflicts economic damage to crops such as beans at

fairly low numbers, 5.) affects both crop yields and commodity quality, 6.) damaging in both the

nymph and adult stages, and 7.) is not well controlled with natural enemies. This is a native insect

to the western part of the U.S. and flourishes in our Mediterranean climate. Research has been

conducted on this pest for 50+ years but management plans must be constantly refined and updated

as conditions change. For a robust management program, biological, cultural, host plant resistance,

and chemical controls should all play a role in lygus bug management. Lygus bug management is

ranked at the top of the research priority list for large limas, baby limas, and blackeyes, so the

importance to the industry is recognized.

_______________________________ 1Larry Godfrey, Evan Goldman, and Mohammad-Amir Aghaee, Dept. of Entomology, Univ. of California, Davis, CA 95616; 2Rachael Long, Cooperative Extension Yolo County, 70 Cottonwood Street, Woodland, CA 95695; 3Steve Temple, Dept. of

Plant Science, Univ. of California, Davis, CA 95616; E-mail: ldgodfrey@ucdavis.edu, In: University of California Dry Bean

Research: 2011 Progress Report published by the California Dry Bean Advisory Board, 531-D North Alta Avenue, Dinuba CA

93618.

27

This research group has been researching lygus bug management in beans for the last several years.

The majority of the research has been in small plots on the UC-Davis Agronomy Farm on baby

limas and at the UC Shafter REC (up through 2009) on blackeyes. We have made progress on this

research as evidenced by the inclusion of studies in 2011 in grower fields (conducted by Rachael

Long in the Sacramento Valley on baby limas and by Carol Frate, under a separate proposal, on

blackeyes in Tulare County). Godfrey and Temple, facilitated by Long, continued to investigate

and refine lygus management on bush and vine baby limas in plots on the UC-Davis Agronomy

Farm. Four areas were researched in 2011 as detailed in the objectives below.

Objectives:

1.) To compare the performance of registered and experimental insecticides against Lygus bugs

in dry beans (‘Luna’ bush baby limas). The results will be evaluated in terms of lygus control,

effects on natural enemies, and protection of bean yield/quality.

2.) To compare the efficacy a newly-registered insecticide, Rimon®, versus a grower standard

against a natural infestation of lygus bugs under a grower field situation. The ability to research

this product in a larger area (~5 acres) will allow for more meaningful evaluation.

3.) To investigate and develop a pest management program for ‘Haskell’ vine baby limas.

a.) incorporating the host plant resistance characteristics to lygus bugs of this cultivar

with targeted insecticide use. Various insecticide timings, frequencies of application,

products, etc. will be evaluated.

b.) designing appropriate ways to sample lygus bugs in ‘Haskell’ vine baby limas such that

populations can be evaluated for treatment decisions.

4.) Extend results to the bean industry via field days, updates to the UC Pest Management Guidelines, etc.

such that the most up-to-date information is available.

Objective 1: Performance of registered and experimental insecticides against Lygus bugs

Insecticidal control for lygus bugs is needed in many fields to protect the crop. Insecticides are an

important production cost and can have other drawbacks including destruction of populations of

beneficials possibly leading to outbreaks of other pests, environmental consequences, regulatory

challenges, etc. An integrated approach, where insecticides are one tool used, is desired but the

severe pest status of lygus mean that insecticides are the primary method of management in many

cases. We are searching for more effective and environmentally-friendly insecticides for lygus

bugs and that has been a goal of this project. Lygus bugs have the ability to develop resistance to

frequently-used insecticides which emphasizes the need to search for new active ingredients. In

recent years, lygus bugs have developed into a significant pest in the eastern half of the U.S.

(different species) and in California on many crops (cotton, strawberries, vegetables, etc.) thus

companies have placed a renewed effort into identifying new products for lygus bugs. Getting these

products into the California bean market is the challenge. In 2010, fourteen different treatments

were evaluated for lygus control, effects on natural enemies, and protection of yield/quality on

‘Luna’ bush baby limas. Rimon® is a newly-registered product for beans and that could be useful

and was evaluated in Objective 2. The experimental products, sulfoxaflor, Carbine®, and Belay

®

also showed promise in 2010 and warranted further evaluations in 2011. Several of these new

chemistries have unique modes of action which fall into the “reduced risk” category. This

facilitates registration but can necessitate changing application timing and practices. These products

do not necessarily quickly kill lygus bugs but disrupt the development and build-up of populations.

28

Methods

Research was done at the UC-Davis Research Farm. Treatments were applied with a backpack CO2

sprayer at 30 GPA. Lygus populations are traditionally very high at this location and we generally

plan on using three applications per season in an attempt to protect the crop. In 2011, these dates

corresponded to 4 Aug. (beans in early bloom stage), 22 Aug. (beans in full bloom), and 2 Sept. (beans

in pod fill stage). Plots of furrow irrigated ‘Luna’ bush baby lima beans were 6 rows x 30 feet with 4

replications in a randomized complete block design. Weekly sweep net sampling of lygus populations

was conducted and lygus bugs adults and nymphs and beneficial insects and spiders were counted.

Plots were harvested on 26 Sept. and yields were calculated. Bean quality, “stings”, etc., was

determined from a subsample. The following treatments were evaluated in 2011.

Table 1. Treatment list for lygus bug management study, 2011

Product *

Product per A

(oz.)

1 Rimon 0.83EC 12 fl. oz.

2 Rimon 0.83EC + Warrior II 12 + 1.92 fl. oz.

3 Rimon 0.83EC + Brigade 2EC 12 + 6.4 fl. oz.

4 Warrior II 1.92 fl. oz.

5 Rimon 0.83EC + dimethoate 4EC 12 + 16 fl. oz.

6 dimethoate 4EC 16 fl. oz.

7 Brigade 2EC 6.4 fl. oz.

8 Untreated ---

9 Carbine 50WG 2.8 oz.

10 Steward EC 11.3 fl. oz.

11 Belay 2.13EC 4 fl. oz.

12 Mustang Max EW 4 fl. oz.

13 Closer 3 fl. oz.

14 Closer 4.5 fl. oz.

* Treatments 9-14 – 0.25% SilWet L-77 added

Results

Arthropod Numbers

Lygus bug populations were high during the early-mid bloom stage and peaked at about 4 per sweep;

the threshold value during this period is ~2 per sweep. During the peak population period, the ratio of

adults to nymphs was about 60:40. Populations declined significantly near the end of August and for

the last three samples dates and last two applications the populations were less than 1 per sweep. The

reason for this decline is unknown. There was a block of later planted beans west of this plot area and

this may have attracted the lygus. Generally at this location, lygus bug populations persist until bean

maturation. Populations of beneficials were present at moderate levels throughout this study.

At 8 DAT, numbers of lygus adults were significantly reduced by Rimon + Warrior, Rimon + Brigade,

Warrior, dimethoate, Brigade, Carbine, Belay, Mustang Max, and Closer (both rates). Reductions

29

ranged from 42 (Carbine, Mustang Max) to 78% (Rimon + Warrior) (Fig. 1). Nymphal populations

were significantly reduced by all treatments by at least 64%. Closer (4.5 oz.) and Rimon + Brigade

showed the greatest reduction in nymphal levels. These same two treatments provided the greatest

reduction in total lygus levels. At 15 DAT, only four treatments significantly reduced the number of

lygus adults. These were Rimon + Warrior, Warrior, Steward, and Closer (3.0 oz. rate). Warrior was

most effective with a 56% reduction. Nymphal lygus were the most numerous on this date of any in

the study. Rimon, Rimon + Warrior, Rimon + Brigade, Warrior, Rimon + dimethoate, dimethoate,

Belay, Mustang Max, Closer (4.5 oz. rate) significantly reduced numbers. Several treatments reduced

levels ~70% and this was the greatest reduction seen relative to the untreated. All treatments except

Brigade, Carbine, and dimethoate reduced numbers of total lygus at 15 DAT. Following the second

application (4 days), lygus levels had overall declined (Fig. 2). Rimon + Brigade, Rimon +

dimethoate, Steward, Belay, and Closer (both rates) significantly reduced numbers of lygus adults by

at least 73%. All treatments except Brigade and Mustang Max significantly reduced numbers of lygus

nymphs relative to the untreated. At 10 days after the second application, lygus adult populations

were low and there were no significant differences among treatments. Lygus nymph populations were

even lower but five of the treatments zeroed the population. On 9 Sept. (7 days after the third

application), levels of Lygus adults, nymphs, and totals were significantly reduced by all treatments

except Brigade. Most reductions were in the 75-100% range. Seasonal totals showed the fewest lygus

adults in the Rimon + Warrior and Warrior treatments (Fig. 3). Lygus nymph populations were lowest

in the Closer (4.5 oz.) and Rimon + dimethoate treatments.

On most dates, there were few significant differences among treatments for numbers of beneficials. At

8 days after the first application, only populations in Belay and both Closer rates differed (were lower)

than those in the Warrior treatment (highest). On the next sample date, populations were lowest in the

untreated and highest in Rimon. The numbers of beneficials can be impacted directly by the treatment

active ingredient but also indirectly if the insecticide reduces numbers of some food item the predators

are feeding on, i.e., with a low level of food reserves they may move. This food item can be some

secondary pest such as aphids, leafhoppers, etc. This makes looking at populations on individual

sample dates difficult. Examination of the seasonal total showed ~ a 2x differences in numbers of

beneficials among the treatments being highest (Rimon) and lowest (Closer [4.5 oz. rate]).

Yield and Quality

Lima bean yields ranged from 3677 to 4096 lbs./A (Table 2). This range is much less than in past

years. Yields in Closer (3.0 oz.) and Belay were significantly lower than those in Rimon, Rimon +

Warrior, Rimon + Brigade, Warrior, dimethoate, Brigade, and untreated; the other treatments had

intermediate yields. Bean damage (stings) was significantly lowest in the dimethoate treatment and

highest in the Steward and Mustang Max treatments. Again the range in damage values was low from

5.4 to 9.6%. The lygus bug populations at this location were lower than normal, of shorter duration,

and developed later in the season thus the impact on yield and quality was minimized.

30

Figure 1. Lygus bug (adults and nymphs) levels pretreatment and at various days after first application.

Figure 2. Lygus bugs (adults and nymphs) at various days after second application, 2011.

31

Figure 3. Seasonal means for lygus bug nymphs, adults, and total and for number of beneficials, 2011.

Table 2. Yield and bean quality results from lygus bug efficacy study, 2011.

Product

Formulation

per A (oz.)

Lima Bean Yield

(lbs./A)

% Stung

Beans

Rimon 0.83EC 12 4011.9 a 8.0 ab

Rimon 0.83EC +

Warrior II 12 + 1.92 4088.3 a 5.7 ab

Rimon 0.83EC +

Brigade 2EC 12 + 6.4 4022.3 a 6.3 ab

Warrior II 1.92 4096.8 a 9.2 ab

Rimon 0.83EC +

dimethoate 4EC 12 + 16 3939.0 ab 7.3 ab

dimethoate 4EC 16 4080.1 a 5.4 b

Brigade 2EC 6.4 3989.4 a 7.0 ab

Untreated --- 4001.3 a 7.0 ab

Carbine 50WG 2.8 3869.6 ab 8.1 ab

Steward EC 11.3 3887.9 ab 9.5 a

Belay 2.13EC 4 3677.2 b 9.4 ab

Mustang Max EW 4 3808.2 ab 9.6 a

Closer 3 3678.6 b 8.4 ab

Closer 4.5 3917.2 ab 7.8 ab

32

Objective 2: Efficacy of Rimon®

insecticide under grower field conditions.

Rimon is an insecticide that was recently (2010) registered for beans. This product was

evaluated in small plots studies from 2008 to 2010 and the performance was moderate. In 2011,

a study was undertaken in Yolo and Sutter counties to look at the impact of Rimon (Novaluron)

for Lygus bug control in lima bean production. Rimon is an insect growth regulator that

prevents nymphs from molting. It does not have efficacy on adult insects. Insect control is by

both ingestion and contact. This insecticide is a low risk material and it has minimal impacts to

non-target organisms. This same active ingredient (Novaluron) is commonly-used and very

effective against lygus bugs in the southern U.S. Their pest lygus is a different species than the

one in California but the behavior and damage is very similar to the western species.

Methods

The trial was a split block design with Rimon at 12 oz/ac tank mixed with a pyrethroid (Warrior

at 1.92 oz/ac or an organophosphate, OP) applied to one part of the field (27 acres) and a

pyrethroid (Warrior at 1.92 oz/ac) or an organophosphate to the rest of the rest of the field (about

50 acres). Treatment was on July 29 in Yolo County and August 1 in Sutter County. Lygus

bugs were sampled with a standard sweep net in each field by taking ten sweep net samples in

four different areas of the field, in each treatment block. Insect samples were taken prior to

treatment and then about every three days for two weeks post treatment. Brigadier at 5.6 oz/ac

(bifenthrin+imidacloprid) was over sprayed over the entire field in Sutter County about a week

after Rimon was applied (August 8). At each field and treatment site, 300 pods were collected,

at random after the fields were cut and windrowed (around August 29 in Yolo County and

September 9 in Sutter County). A subsample of 300 beans were taken from the pods, weighed

and scored for lygus stings.

Results

Rimon suppressed nymphs by about 30% in both sites at peak counts compared to the Warrior or

organophosphate treatments (Figures 4 and 5). However, adult counts were about the same in

both treatments (Figures 6 and 7). The number of stings per 300-beans was less than 0.5% in

both treatments at each site. There were no differences in seed weights between the Rimon and

Warrior or organophosphate treatments. Sutter County weights were 93±1 grams for both

treatment plots and Yolo County weights were 101±1 grams for both treatment plots.

In conclusion, Rimon is an effective insect growth regulator that will help suppress lygus

nymphs in lima bean production. This material is used with good success in controlling lygus in

strawberries and cotton. However, since it does not control adult lygus, it must be tank mixed

with another insecticide that has efficacy on adult lygus bugs, which may not be economical in

dry bean production.

33

Figure 4. Number of lygus nymphs per sweep, lima beans, Yolo County 2011. Field

treated with Rimon+Warrior and Warrior alone.

Figure 5. Number of lygus nymphs per sweep, lima beans, Sutter County 2011. Field treated

with Rimon+organophosphate and an organophosphate alone. Entire field over treated with

Brigadier about a week after the Rimon treatment.

34

Figure 7. Number of adult lygus bugs per sweep, lima beans, Sutter County 2011. Field treated

with Rimon+organophosphate and an organophosphate alone. Entire field over treated

with Brigadier about a week after the Rimon treatment.

Figure 6. Number of adult lygus bugs per sweep, lima beans, Yolo County 2011.

Field treated with Rimon+Warrior and Warrior alone.

35

Objective 3: Develop a pest management program for ‘Haskell’ vine baby limas

The host plant resistance characteristics to lygus bugs in Haskell cultivar, with targeted

insecticide use, were studied in replicated field plots. Host plant resistance is an excellent pest

management tool for many crops/pests. The lower cost of this type of management, lack of

environmental hazard and reduced incidence of other problems such as insecticide resistance,

compared with insecticides, are significant advantages. Host plant resistance often does not

provide complete pest control and, with cases such as lygus bugs, the remaining pests may still

inflict economically-important damage. This can be mitigated by combining host plant

resistance with other approaches including the targeted use of insecticides. This is the approach

examined in this study.

Supplemental lygus control with insecticides. ‘Haskell’ is a vine baby lima bean that has been

developed by Steve Temple. This cultivar may function as a stand-alone tool under low to

moderate lygus pressure and under high pressure it may be combined with an insecticide to

provide cost-effective lygus management. Given the properties of this cultivar to withstand

lygus bugs, the highest level of supplemental control from an insecticide is not needed. Instead,

a “bump” in lygus bug control may be a more viable approach when growing ‘Haskell’ and this

added control can be achieved with a “soft” insecticide. Some soft insecticides will provide

excellent control and some of those are under development and a few years from any possible

registration. One product, Steward, is in the registration pipeline and, from my experience, one

can expect ~60-70% lygus control from an application. The advantage of “soft” products is that

they help to preserve populations of natural enemies – predators and parasitoids. Therefore, this

may avoid the use of treatments for bean aphids, armyworms, leafminers, and spider mites (these

pests often build-up where natural enemies populations have been compromised). Spider mites

and aphids have been severe pests of limas in some parts of the SJV and this has resulted in

additional costs to control these pests. The severity of the lygus infestation and likelihood of

aphids and/or spider mites in each particular location will influence the management regime.

Methods

Vine lima beans were planted on the UC Davis Agronomy Farm on 27 May; two bean cultivars

were compared Mezcla and Haskell. Within each cultivar, various insecticide management

approaches were used, 1.) a broad-spectrum insecticide, Mustang Max EW at 4.0 fl. oz. per A

and 2.) a “reduced risk” insecticide, Steward EC at 11.3 fl. oz. per A. In terms of lygus bug

control, Mustang Max will likely be better than Steward but coupled with the host plant

resistance characteristics of Haskell, Steward is hypothesized to provide adequate lygus

management. The third factor considered was application intensity. In 2011, the two

insecticides were applied at bloom (4 Aug.) or pod fill (2 Sept.) or with both timings.

Treatments were applied to plots measuring 6 rows wide by 30 feet long with each treatment

replicated four times. Applications were done with a CO2 backpack sprayer at 30 GPA. Lygus

bug populations were sampled with a sweep net at approximately weekly intervals with bugs

separated into nymphs and adults. Finally, bean yields and seed quality were determined from

two rows of each plot on 13 October.

36

Results

Lygus bug populations were slow to develop in this vine baby lima bean plot. The first treatment

timing was on 4 Aug. when lygus bug levels were increasing. As shown in Fig. 8A, the

untreated plots (designated as late or untreated) had ~0.5 lygus per sweep. The population was

~75% adults and 25% nymphs. There were no obvious differences in numbers between the two

cultivars. For the two insecticides, Mustang was slightly more effective than Steward but both

showed activity (the early and both treatments received insecticides 8 days before these data

were collected). Data from 26 Aug. (Fig. 8B) were collected during the period of peak lygus

populations. However, the highest numbers were ~1.5 lygus per sweep with more adults and

nymphs. Fig. 8C data were collected 1 week after the late application timing (the “both”

treatment also received insecticides). Lygus bug populations were overall reduced and mostly

comprised of nymphs.

Yields varied among treatments but there were no trends or significant differences (Fig. 9). The

only significant difference in yields was among blocks, i.e., position in field. Block 4 (west end

of field) had lower yields than the other three blocks. These yields from block 4 were deleted

and the results shown in Fig. 9 are from blocks 1 to 3. The reason for this difference is

unknown. Overall, the lygus bug population was not high enough and did not occur early

enough in the season the impact bean yields. The highest population seen was ~1.5 lygus per

sweep in late Aug. This level of the pest at this late date (3 months after planting) would not

have any effects on bean set and yield.

Sampling Lygus bugs in vine baby limas. The second area of research for vine baby limas

(‘Haskell’) was determining how to best sample the vine canopy for lygus bugs. The lygus

resistance bred into this variety means that an “automatic” lygus insecticide treatment will not be

needed in many cases. This places an added importance on being able to assess the lygus

population in order to make a treatment decision. The sweep net is the standard way to assess

lygus bug levels in beans. But the dense, interwoven growth of the vine limas makes the net

difficult to efficiently use for sampling, compared with bush baby lima beans.

Methods

Plots (10 rows wide x ~80 ft. long with 3 reps) of Haskell vine and Beija-Flor bush baby limas

were grown on the UC Davis Agronomy Farm and were naturally infested with lygus bugs.

Three sampling methods were conducted in each bean type at about weekly intervals from 22

July to 9 Sept., 1.) the standard sweep net (6 sets of 10 sweeps), 2.) D-vac suction samples – a

method which should better remove lygus bugs from deep in the canopy (6 sets of suctions each

covering 10 sq. ft.), and 3.) a 2 sq. meter confined area that was destructively sampled and all

plant material and therefore lygus bugs counted. Collected lygus bugs were separated by sex and

adults vs. nymphal instars. The sampling as described above was all done mid-morning (~9 to

10 am) and mid-afternoon (~2 to 3 pm). The comparison and relationship between populations

sampled in the vine and bush beans will allow us to better design and sampling method/program

to be used by PCAs.

37

Figure 8. Lygus bug populations per sweep (separated by nymphs and adults) in vine baby lima bean

management study. Bean cultivar, treatemnt timing and insecticdes were examined as factors. A.) data

from 12 Aug., B.) data from 26 Aug., C.) data from 9 Sept.

A

B

C

38

Figure 9. Vine baby lima bean yields with two cultivars, and a range of insecticide treatments for lygus

bug management, 2011.

Results

Results, summarized across all sample dates, are shown in Fig. 10. Numerous factors were

examined in this study so I will briefly summarize the most important findings. Comparing the

sweep net results vs. the vacuum in the two bean types shows that the vacuum sampler captured

slightly more lygus than the sweep net in the vine beans. The vacuum machine should operate

independent of bean crop canopy and give a better representation of the real number of lygus in

the beans. It appears the vine beans have more lygus per unit area than the bush beans (the soil

surface areas sampled were the same between the two bean types but the additional height of the

vine canopy must be considered). Looking at the sweep net data, the opposite results are seen.

There were more lygus captured with the sweep samples in the bush beans than in the vine beans

– about twice the number. The sweep net cannot efficiently sample the lygus popualtion in the

vine beans due to the canopy. It appears that numbers obtained with the sweep net in vine beans

should be doubled to equilibrate to numbers collected with the sweep net in the bush beans. This

could be important for treatment decisions. The second conclusion is that the numbers with the

sweep net are lower, by about 25%, with an afternoon sampling than a morning sampling in both

bean types. This difference is due to capturing fewer adult lygus in the afternoon than the

morning. The reason for this is either the adults move deeper in the canopy in the afternoon to

avoid the heat or that they are more active and avoid (fly off) the sweep net. The same result

was not seen with the nymphs or in the vacuum samples. This small difference may not be

critical for treatment decision but should be considered.

39

Figure 10. Influence of bean type (vine versus bush) and time of day of sampling lygus bugs and

assessing populations for a treatment decision, 2011.

Objective 4: Extending results to the bean industry.

The UC pest management guidelines will be modified at the next opportunity for revision.

Results and field plots were highlighted to the industry during the UC Davis bean field day in

Aug. 2011 organized primarily by Long and Temple. Other venues for getting results to the

industry will be explored and conducted as appropriate.

SUMMARY

Host plant resistance, biological control, and reduced risk insecticides are fundamental aspects of

integrated pest management programs and research was conducted to strengthen all of these in

the baby lima bean system. The key pest, western tarnished plant bugs (lygus bugs) was the

target of this research. Registered and experimental insecticides were evaluated in small field

plots and in grower fields. Several products effectively controlled a low to moderate level of the

pest in research plots. Two experimental products, Carbine and Closer, which also had minimal

effects on populations of natural enemies (predators and parasitoids) were most promising for the

future. Rimon is an insect growth regulator that was recently registered on beans. In large

grower field plots, this active ingredient showed activity on lygus bug nymphs. However, the

need to tank-mix Rimon with an adult-active product (since both lygus stages are always present

in bean fields) appears to limit the cost-effectiveness. ‘Haskell’ vine baby lima beans appear to

have a significant role in lygus bug management because of its ability to withstand a low of

lygus bug infestation. Under heavy lygus bug pressure, this variety is not a stand-alone tool and

control must be supplemented by insecticides. The selection of insecticides and appropriate

timing were explored in field plots but a late-developing lygus bug population limited the

appropriateness of this work. Sweep net sampling for lygus bugs to make informed treatment

decisions in vine baby limas was also studied. A 2X adjustment factor needs to be used in vine

baby limas to compensate for the inefficiency created by the dense canopy.

Acknowledgements. The technical assistance of Chip Morris was critical as well as the Godfrey

lab student assistants, Jennifer Mueller, Tara Trakin, Brandon Anson, and Gregory Finkelstein.