Development and Evaluation of IPM Systems Components for Insect Pests and Pathogens of Cucurbit Crops in the Southeastern U.S.

Progress report for LS20-337

Project Type: Research and Education
Funds awarded in 2020: $299,935.00
Projected End Date: 03/31/2023
Grant Recipients: Virginia Tech Department of Entomology; North Carolina State University; Clemson University
Region: Southern
State: Virginia
Principal Investigator:
Dr. Thomas Kuhar
Virginia Tech
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Project Information


Managing insects in cucurbit crops is a longstanding challenge due to conflicting needs of intense pest management and strong pollination services. The cucurbit pest complex is notoriously problematic because it includes insects that inflict considerable feeding damage and are also vectors of pathogens that threaten total crop loss. Intense broad-spectrum pesticide use can harm predatory insects and pollinators that are critical for profitable yields. Stronger cultural tools and more selective insecticides are needed to limit pest pressure and conserve ecosystem services by beneficial insects. Colored and reflective mulches are commonly employed to promote plant growth and repel herbivores, but their effects on predator and pollinator attraction are unclear. Likewise, living mulches planted between plastic-mulched rows may buffer the effects of insecticide applications on beneficial insects by providing refuge habitat. However, ecosystem services and potential disservices associated with living mulches in conventionally-managed systems are not well-documented, and for that reason, they are rarely incorporated in conventional vegetable production. To that end, we propose a research project and a series of experiments manipulating colored mulches, living mulches, and applications of broad spectrum and selective insecticides across three Southeastern states. We will develop novel cultural tools that better harmonize chemical and biological control, and evaluate their utility in an economic framework that balances risks, costs and benefits in each system. We will also demonstrate and deploy these tools by engaging with growers in workshops, field days, and grower conferences across the Southeast.

Project Objectives:

Objective 1. Determine the effects of colored plastic mulch on the production of cucumber and squash and their pest and beneficial insect communities

Objective 2. Harmonize chemical and biological control in cucurbit systems by integrating plasticulture with living mulches between beds

Objective 3. Assess the impact of augmentative releases of the egg parasitoid Gryon pennsylvanicum on squash bug populations in squash.

Objective 4. Estimate the economics of different plastic mulch colors, living mulches between beds, and reduced risk pesticides (VA team-Alford)


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Materials and methods:

Objective 1 Effects of colored plastic mulch on cucurbit production and insect communities.  

To determine how mulch coloration affects yield, and identify areas of plasticulture for further research/utilization, summer squash and trellised cucumbers were planted in a Latin Square design with four blocks, ~4.5 m in length. The experiment was conducted in two locations in 2019, Kentland Farm in Whitethorne, VA and Homefield Farm in Whitethorne, VA, and conducted in three locations in 2020, the same two aforementioned locations as well as the Southwest Minnesota State University Research Farm in Marshall, MN.  Four different plastic mulch treatments were used: Black, white, aluminum (reflective), and bare ground.  Squash and cucumbers were directly sown mid-June at 2-3 ft spacing within each bed.

Once the squash plants possessed 4-6 leaves (first week of July), we began sampling for squash bug adults, egg masses, and nymphs.  We sampled five randomly-selected plants (about half the plants within each plot) through a visual check of all parts of each plant, as well as the plastic mulch directly below the plants.  Squash bug sampling was conducted for six consecutive weeks.  Yield within each plot was also collected once the plants reached maturity.  Yield collection was taken three times per week for three consecutive weeks and only undamaged fruit was counted.

To compare insect counts among treatments, we used a Generalized Linear Mixed Model (GLMM) with mulch type and sample date as fixed effects and plot location within the experiment as a random effect.  All insect count data were transformed using a Log(x+1) correction.  When necessary, Tukey Kramer HSD (P < 0.05) was used to determine significant differences between treatments. To compare yield among treatments, a one-way ANOVA was used.

Pollinators. In 2020 only, pollinators were sampled in the experiment.  Plots were visited by 4 observers on days when the weather was favorable for bee activity; clear skies and temperatures reached above 70 degrees Fahrenheit with low wind speed, modified from methods used by Adamson et al. (2012). For each row in the 4 plots of the color mulch study, the 50 m row was split in two and half contained cucumbers (Cucumis sativus) and half contained zucchini (Cucurbita pepo) (alternating from row to row as to which crop was planted first).  Pollination was defined when bees made contact reproductive parts. Observers walked up and down each half section for 90 seconds (in total 3 mins per row plot), observing bees landing and the flower sex on which pollination occurred.  Bees were classified in 9 main morpho-taxa categories: honey bees, bumble bees, squash bees, large black bee, small black bee, large striped bee, small striped bee, small striped green, green bee, and other (McGrady et al. 2019). Representatives for observed morpho-taxa were collected and will be identifed to species using Droege (2010).


Objective 2. Harmonize chemical and biological control in cucurbit systems by integrating plasticulture with living mulches between beds

This portion of the project will examine potential ecosystem services (pollination, pest control) and disservices (competition with crops, pest attraction, pathogen susceptibility) conferred by living mulches in combination with standard insecticide treatments in yellow squash crops grown on black plastic mulch. The experiment will be set up in 2021 at five locations and will assess the effect of a living mulch plant mixture of teff grass, buckwheat and red clover sown between plastic-mulched rows compared to bare ground between plastic beds on the insect pest and beneficial community in a squash production agroecosystem.  We will also assess each mulch treatment under routine insecticide applications versus no insecticides.  We predict that a buckwheat, clover, teff grass living mulch will provide habitat resources that can buffer effects of insecticide treatments on beneficial insects (Hooks et al. 1998, Lee et al. 2001, Frank and Liburd 2005). Therefore, we hypothesize that pest pressure will be lowest in living mulch treatments.


Objective 3. Assess the impact of augmentative releases of the egg parasitoid Gryon pennsylvanicum on squash bug populations in squash.

Squash bug and egg parasitoid Gryon pennsylvanicum (Fig. 1) lab colonies were established from wild collected individuals in Whitethorne, VA during the 2019 field season.  From August 2019 to June 2020, G. pennsylvanicum populations were reared on squash bug eggs and lab parasitism data was collected.  Our lab rearing data focused on the wasp’s parasitism rates, progeny sex ratio, and development time (i.e., number of days from parasitism to emergence).  These data were pivotal to determine how many parasitized eggs would need to be deployed at each release site in order to achieve a release rate of about 2-3 female wasps per plant.

Fig. 1. Primary egg parasitoid of squash bug.

We chose three organic farms: (1) Fritillary Farm (Suffolk, VA), (2) Seafield Farm (Cape Charles, VA), and (3) Shine and Rise Farm (Painter, VA), in southeastern VA to be our G. pennsylvanicum release sites.  This geographic area of Virginia was chosen based on previously conducted G. pennsylvanicum survey data, which suggested that southeast Virginia has low rates of squash bug egg parasitism by the wasp (Wilson and Kuhar 2017).  Three non-release control sites were also established and paired with the closest release site.  Overall, all study sites needed meet the following criteria: (1)  at least 100 summer squash plants, (2) history of squash bug presence, & (3) no use of insecticides within squash plots.

On June 29th and 30th 2020, parasitized egg masses were deployed at each release site.  As mentioned above, a release rate of roughly 2-3 female parasitoids was estimated given the number of total parasitized egg masses deployed (see lab rearing results below).  Two weeks following the releases, we began collecting squash bug egg masses at each research site.  In total, we collected egg masses on three separate dates at two week intervals.  Collected egg masses were monitored in lab for wasp emergence and nymph hatch.  Each egg mass collected was labeled as either “parasitized” (i.e., 50% parasitism or greater) or unparasitized (i.e., < 50% parasitism).  We were also able to calculate accurate parasitism and nymph emergence rates with egg masses collected at one of the paired release/no release sites. Complications with wasp deployment at one our release sites (Shine and Rise Farm) resulted in us dropping the site from statistical analyses.  We used a one-way ANOVA to compare egg collection data among paired release and no release sites. 

Additional releases sites are planned for 2021 including some in Georgia and North Carolina.

Objective 3b (Impacts of insecticides on G. pennsylvanicum). Laboratory colonies of G. pennsylvanicum established from wild-collected parasitized squash bug egg masses in 2019 near Whitethorne, VA, will be used for this objective. Parasites will be reared on squash bugs eggs produced from a laboratory colony. Colonies of both the pest and parasitoid will also be started in NC and SC during the 2020 field season with individuals from the VA colonies.

            Negative effects of broad-spectrum insecticides (e.g., pyrethroids, neonicotinoids) on natural enemies have been well documented. However, less is known about the effects of reduced risk insecticides and fungicides. Laboratory experiments at Virginia Tech have demonstrated significantly reduced mortality in selective (flupyradifurone, flonicamid, pyrifluquinazon) compared to broad spectrum (sulfoxaflor, lambda-cyhalothrin) insecticides [Kuhar et al. unpublished]. Here, we will perform behavioral observations between G. pennsylvanicum females and their host after or during different modes of insecticide exposures. These modes of exposure include the wasp’s contact with an insecticide-treated surface, contact with a treated host egg mass, and potentially from feeding on leaf exudates. Following exposure to a treated surface (filter paper), a host egg mass will be provided to see if the wasp is capable of successful host parasitism. A similar experiment will be performed using insecticide-treated egg masses. Wasp will be exposed to treated egg masses and parasitism recorded. Bioassays will be recorded using EthoVision motion tracking software to quantify parasitoid behavior (host antennation, mounting, and probing). Insecticides chosen for this portion of the project will be based on insecticides used in Objective 2.

            Cucurbit growers often utilize neonicotinoid soil drenches at transplant to protect seedlings. These compounds translocate to cucurbit pollen and nectar, at concentrations within the range of sublethal effects in some beneficial insects [Dively and Kamel 2012]. As G. pennsylvanicum is known to feed on cucurbit leaf exudates [Olson and Nechols 1995], tests exposing wasps to plants grown from neonicotinoid treated seeds or soil drenched plants will also be conducted to assess whether or not feeding on the leaf exudates of treated plants affects parasitoid survivorship. Neonicotinoid concentrations in exudates will be quantified using LC-MS-MS to estimate the range of concentrations.

            The final component to our behavioral observations will include repellency assays to determine if G. pennsylvanicum females will forage for hosts on surfaces treated with botanical insecticides used in organic systems, as they have been noted as having a repellent effect on parasitoids. Repellency behaviors exhibited by the parasitoid will be characterized using EthoVision software. Trials with no insecticide exposure will serve as control treatments. All laboratory assays will be performed from September 2020 to September 2022.


Objective 4 (Economic assessment). We will leverage existing Clemson University crop enterprise budgets for fresh market cucumbers and yellow squash [Clemson Cooperative Extension 2016a,b ] to conduct partial budget analyses to evaluate the economic feasibility of the cultural and chemical control treatments in objectives 1-3. These tools quantify input costs (e.g. fertilizer, pesticide, herbicides) of each approach and balance them with dynamic crop prices that vary according to time of year (spring or fall) and production market (organic and conventional). This approach will follow that of Alford and Krupke [2018], and determine break-even prices. In short, economic analysis will utilize field data to parameterize a probability density function, which can then be used to calculate the minimum treatment-associated-yield increase needed to recover treatment costs. This value serves as a “breaking even” point and provides the probability that a grower will recover the costs associated with a cultural management approach. Quantifying savings from reductions in pesticide applications across colored and living mulch treatments, along with potential risks of pathogen vulnerability and yield loss, we will demonstrate the value of each approach and aim to catalyze grower adoption.


Research results and discussion:

Objective 1 Effects of colored plastic mulch on cucurbit production and insect communities.  

Effects of plastic mulch on squash yield

In 2019, at Kentland Farm, no significant differences in marketable fruit yield were observed among treatments (F=1.631, P=0.058), even though the mean number of marketable fruit from the reflective mulch plants was nearly double the yield of the control plants. However, at the Homefield Farm location, we observed significant differences in marketable fruit yield among treatments (F=3.663, P=0.0199), as plants in black mulch treatments produced more fruit than plants in white mulch and control treatments (P<0.05).

In 2020, at Kentland Farm and Homefield Farm, no significant differences in squash yield were found among treatments.  

Cumulative number of squash fruit harvested during a three-week period grown under different plastic mulches in Virginia.

Effects of plastic mulch on cucumber yield

In 2019, at Kentland Farm, we observed a significant treatment effect on mean cucumber yield  (F=6.798, P=0.0004); plants in reflective and black mulch treatments produced significantly more fruit than the control plants (P<0.05). At Homefield Farm, significant differences in cucumber fruit yield was observed among treatments (F=23.99, P<0.0001).  Plants in black mulch produced significantly more fruit than all other treatments (P<0.05).  Plants in the reflective mulch also produced more fruit than plants in the white mulch (P<0.05).

In 2020, at Kentland Farm , no significant differences in cucumber yield were found among treatments (F=0.6825, P=0.567).  At Homefield Farm, significant differences in cucumber yield were observed among treatments (F=4.154,P=0.009); plants in the reflective and white mulch produced significantly more fruit than plants in the control treatment (P<0.05).  

Cumulative number of cucumber fruit harvested during a three-week period grown under different plastic mulches in Virginia.

Squash bugs. Squash bugs were the dominant pest found in the mulch experimental squash plots.  There was an overall significant effect of mulch treatment on densities of egg masses, nymphs, and adults with more squash bug life stages tending to accumulate on plastic mulch treatments, especially black and reflective mulch compared with bare ground. 

In 2019, at Kentland Farm, we observed a significant difference in mean egg mass counts among mulch treatments (F=5.937, P=0.0002).  Squash plants in the black and reflective mulch had significantly more egg masses than the control plants (Tukey HSD, P<0.05). We observed a significant difference in mean nymph counts among mulch treatments (GLMM, F=3.1785, P=0.0303). More nymphs were found on plants in the black mulch treatments than on the control plants (P<0.05).  We observed a significant difference in mean adult counts among mulch treatments (GLMM, F=3.598, P=0.0175). More adults were found on plants in the white mulch treatments than on the control plants (P<0.05).

At the Homefield Farm location there was no significant treatment differences in egg mass counts  (F=1.492, P=0.192) or nymph densities (F=2.326, P=0.131).  However, significant effects on adult counts were observed among treatments (F=12.13,P=0.0008), as more adults were found on reflective mulch plants than on plants within all three other treatments (P<0.05).

In 2020, mulch treatment had a significant effect on squash bug egg masses (F = 3.958, P = 0.0356) at the Homefield Farm location, however there was no treatment effect on egg masses at the Kentland Farm location (F = 0.888, P = 0.475).  At the Homefield site, plants in reflective mulch plots possessed more egg masses than plants in bare ground plots (P = 0.0338). There was no significant difference between the white mulch and bare ground (P = 0.0773) or black mulch and bare ground (P = 0.276). 

No differences in squash bug nymph counts were observed among mulch treatments at either Homefield Farm (F = 0.799, P = 0.518) or Kentland Farm (F = 0.2894, P = 0.0791).  However, mulch treatment did have a significant effect on squash bug adults (F = 3.957, P = 0.0352) at the Homefield Farm location, however there was no treatment effect on adults at the Kentland Farm location (F = 1.378, P = 0.297).  At the Homefield site, plants in white mulch plots possessed more adults than plants in bare ground plots (P = 0.0224). There was no significant difference between the reflective mulch and bare ground (P = 0.226) or black mulch and bare ground (P = 0.375).

Pollinators.  Squash bee was the dominant pollinator found in both squash and cucumber in Whitethorne, VA (see figures below).  There was no significant effect of mulch type on counts of bees or on the distribution of bee types (morphotypes).   

Bees recorded in squash flowers grown on different plastic mulch types in Whitethorne, VA in 2020.
Bees recorded in cucumber flowers grown on different plastic mulch types in Whitethorne, VA in 2020.

Discussion - Plastic mulches: The agronomic and weed suppression benefits of growing vegetables on plastic mulch are well documented (Decoteau et al. 1986, Lament 1993, Greer and Dole 2003, Andino and Motsenbocker 2004).  Colored mulches in particular aluminated (silvery) or reflective mulch have also been shown to suppress a number of insect pest species of vegetables (Wolfenbarger and Moore. 1968, Cartwright et al. 1990, Henshaw et al. 1991, Caldwell and Clarke. 1999, Greer and Dole 2003, Nyoike and Liburd. 2010).  Our researched showed similar results as others with black and silvery reflective mulches tending to yield higher numbers of cucumbers and squash compared to bare ground beds.  The reasons for these differences are not completely known, but are likely related to increased soil temperature and moisture retention resulting in greater plant growth and productivity.  No effects of plastic mulch on pollinators were detected. However, greater densities of all life stages of squash bugs were found on plastic mulch plots compared to bare ground beds.  Squash bug adults like to seek shelter in the planting hole of plastic mulch and consequently deposit more eggs on those plants.   

Objective 2. Harmonize chemical and biological control in cucurbit systems by integrating plasticulture with living mulches between beds

This objective will begin in summer 2021.  


Objective 3. Assess the impact of augmentative releases of the egg parasitoid Gryon pennsylvanicum on squash bug populations in squash.

Egg parasitoid lab rearing

Our G. pennsylvanicum colony successfully parasitized 79.7% of all eggs when mated female wasps were exposed to squash bug egg masses (N=58) under laboratory conditions.  Emerged wasps had a female biased sex ratio of 6.26 females to 1 male. Mean development time was calculated to be 24.4 days.

Egg collections

A sample of >100 squash bug egg masses was collected from each of two release sites versus two non-release control sites.  Squash bug parasitism was significantly higher in the release farms than the non-release farms (F = 7.201, P = 0.0188). 

Gryon pennsylvanicum appears to be a promising biological control agent for squash bug in the U.S.(Olson and Nechols 1995, Olson et al. 1996, Cornelius et al. 2016).  Our research has paved the way for mass rearing of the parasitoid as well as inoculative releases strategies to increase biological control levels of squash bug.  

Objective 4 (Economic assessment). This will be done in 2022.


Adamson, N. L., Roulston, T. H., Fell, R. D., & Mullins, D. E. (2012). From April to August—Wild Bees Pollinating Crops Through the Growing Season in Virginia, USA. Environmental Entomology, 41(4), 813–821.

Alford and Krupke. 2018. A meta-analysis and economic evaluation of neonicotinoid seed treatments and other prophylactic insecticides in Indiana maize from 2000-2015 with IPM recommendations. J. Econ. Entomol. 111:689-699
Andino and Motsenbocker. 2004. Colored plastic mulches influence cucumber beetle populations, vine growth, and yield of watermelon. HortScience. 39:1246-1249.
Caldwell and Clarke. 1999. Repulsion of cucumber beetles in cucumber and squash using aluminum-coated plastic mulch. HortTechnology. 9:247-250.
Cartwright et al. 1990. Influence of crop mulches and row covers on the population dynamics of the squash bug (Heteroptera: Coreidae) on summer squash. J. Econ. Entomol. 83:1988-1993.
Clemson Cooperative Extension. 2016a. Yellow squash-for fresh market irrigated.
Clemson Cooperative Extension. 2016b. Spring cucumber-for fresh market irrigated.
Cornelius et al. 2016. Impact of the egg parasitoid, Gryon pennsylvanicum (Hymenoptera: Scelionidae), on sentinel and wild egg masses of the squash bug (Hemiptera: Coreidae) in Maryland. Environ. Entomol. 45:367-375.
Decoteau et al. 1986. Mulch surface color affects yield of fresh-market tomatoes. J. Amer. Soc. Hort. Sci. 114:216-219.
Dively and Kamel. 2012. Insecticide residues in pollen and nectar of a cucurbit crop and their potential exposure to pollinators. J. Agric. Food. Chem. 60:4449-4456.

Droege, S. (2010). The Very Handy Manual: How to Catch and Identify Bees and Manage a Collection.

Frank and Liburd. 2005. Effects of living and synthetic mulch on the population dynamics of whiteflies and aphids, their associated natural enemies, and insect transmitted plant diseases in zucchini. Environ. Entomol. 34:857-865.
Gibson et al. 2011. Effect of a living mulch on weed seed banks in tomato. WeedTech. 25:245-251.
Greer and Dole. 2003. Aluminum foil, aluminum-painted, plastic, and degradable mulches increase yields and decrease insect-vectored viral diseases of vegetables. HortTechnology. 13:276-284.
Hartwig and Ammon. 2002. Cover crops and living mulches. WeedSci. 50:688-699.
Henshaw et al. 1991. Use of reflective mulches in control of mosaic viruses in summer squash. Natl. Agr. Plastics Congr. Proc. 23:78-83.
Hooks et al. 1998. Incidence of pests and arthropod natural enemies in zucchini grown with living mulches. Agric. Ecosyst. Environ. 69:217-231.
Lament. 1993. Plastic mulches for the production of vegetable crops. HortTechnology. 3:35-39.
Lee et al. 2001. Refuge habitats modify impact of insecticide disturbance on carabid beetle communities. J. Appl. Ecol. 38:472-483.

McGrady, C. M., Troyer, R., Fleischer, S. J., & Strange, J. (2019). Wild Bee Visitation Rates Exceed Pollination Thresholds in Commercial Cucurbita Agroecosystems. Journal of Economic Entomology, 113(2), 562–574.

Nyoike and Liburd. 2010. Effect of living (buckwheat) and UV reflective mulches with and without imidacloprid on whiteflies, aphids and marketable yields of zucchini squash. Int. J. Pest Manage. 56:31-39.
Olson and Nechols. 1995. Effects of squash leaf trichome exudates and honey on adult feeding, survival, and fecundity of the squash bug (Heteroptera: Coreidae) egg parasitoid Gryon pennsylvanicum (Hymenoptera: Scelionidae). Environ. Entomol. 24:454-458.
Olson et al. 1996. Comparative evaluation of population effect and economic potential of biological suppression tactics versus chemical control for squash bugs (Heteroptera, Coreidae) management on pumpkins. J. Econ. Entomol. 89:631-639.
Wilson and Kuhar. 2017. A survey of the species of squash bug (Hemiptera: Coreidae) egg parasitoids in Virginia and their distribution. J. Econ. Entomol. 110:2727- 2730.
Wolfenbarger and Moore. 1968. Insect abundances on tomatoes and squash with aluminum and plastic sheetings. J. Econ. Entomol. 61:34-36.

Participation Summary
7 Farmers participating in research


Educational approach:

Three graduate students are being trained under this grant project:

Ph.D. student, Sean Boyle, Department of Entomology, Virginia Tech - began his program in 2019.

M.S. student, Courtney Walls, Department of Entomology, Virginia Tech - began her program in 2020.

M.S. student, Allison Stawara, Department of Entomology, University of Georgia - began her program in 2021.  

Educational & Outreach Activities

1 Curricula, factsheets or educational tools
3 On-farm demonstrations
4 Online trainings
19 Webinars / talks / presentations
3 Workshop field days

Participation Summary:

520 Farmers
17 Ag professionals participated
Education/outreach description:

Wilson, James M.; Day, Eric; Kuhar, Thomas P. 2000. Striped Cucumber Beetle. Virginia Cooperative Extension Publication No. AEE-72.


Boyle, Sean, Thomas Kuhar, and Donald Weber. 2000. Reevaluating thresholds for squash bug, Anasa tristis, life stages in summer squash (Cucurbita pepo) systems2020 Entomology Virtual Meeting: Annual Meeting of the Entomological Society of America, November 11-25, 2020, Orlando, FL - Virtual.

Walls, Courtney, James Wilson, and Thomas Kuhar. 2020. What’s the buzz in Virginia cucurbits: Three trapping methods to survey pollinators. 2020 Entomology Virtual Meeting: Annual Meeting of the Entomological Society of America, November 11-25, 2020, Orlando, FL - Virtual.

Walls, Courtney. 2020. Beekeepers at Virginia Tech Virtual Meeting,– “Pollinators you can find in Virginia Cucurbits” October 27, 2020 – Virtual - Attendance: 25

Walls, Courtney, James Wilson, and Thomas Kuhar.  2021. Virginia Pumpkin Growers Association–  “ What we found in Virginia Pumpkins” February 9,  2021- Virtual - Attendance: 30

Walls, Courtney. 2021. "Ask an Entomologist Virtual Field Trip", North Wilkes Middle School (Wilkes Country Schools, NC),– “Bees around you” – March 18, 2021 -Virtual -Audience: 100+

Kuhar, T. 2000. Insect pest update. Cucurbit Crops Session: Southeast Virginia Fruit and Vegetable Conference, Chesapeake, VA, Feb 27, 2000.

Kuhar, T. 2000. Vegetable pest IPM info in virtual Zoom Meeting on Vegetable Gardening Resources – VCE, Virginia Beach, VA, March 27 – 40 people

Kuhar, T. 2000. Vegetable IPM update. VCE Ag Today meeting focused on vegetable production, May 7 – 40 people

Kuhar, T. 2000. Insect pest control. IPM Ask the Expert – Teleconference, Radio show – Mid-Atlantic U.S., May 27 – 50 people

Kuhar, T. P. and D. Owens. 2020. Seasonal Insect Management for Vegetable Crops:  Protecting Beneficial Insects While Minimizing Insect That Damage Vegetable Crops. 2020 Virtual Vegetable Grower Meetings, Virginia Coop. Ext., June 24, 2020.

Kuhar, T. 2000. Vegetable IPM update. Northern Virginia Virtual Vegetable Meeting, June 24, 40 people

Kuhar, T. P. 2020. Update on insect management. LATE SEASON Virtual PUMPKIN MEETING, Virginia Pumpkin Growers Association, S E P T EMB E R 1 6, 2020.

Kuhar, T. P. 2020. Fall Vegetable Pest Updates, VCE AG Today Virtual Meeting, October, 29, 2020.

Kuhar, T. P. 2020. Fall Vegetable Pest Updates, Shenandoah Valley Vegetable Grower Virtual Meeting, October, 29, 2020.

Kuhar, Thomas. 2020. Pest Management Update for Cucurbits. Northern Neck Vegetable Growers Association Meeting, Virtual.

Kuhar, T., J. Wilson, and C. Walls. 2021. Insect control and pollinators. Virginia Pumpkin Growers Association 2021 Annual Meetings. Virtual. Hillsville, VA. Feb 9, 2021.

Virginia Biological Farming Virtual Conference. March 18, 2021

Kuhar, T. 2001. Organic options for battling insect pests. Organic Production Agent In-service Training. Roanoke, VA. March 24 & 25, 2021. Virtual.

Kuhar, T. 2021. Managing insect pests. Vegetable Crop Production for Urban Agriculture. Virginia Cooperative Extension In-Service Agent Training, March 2 and 3, 2021. Virtual.

Alford, A. 2020. Demonstrated colored mulch research plots.  Southwest Minnesota State University Field Day. Marshall, MN. Aug 5, 2020.

Alford, A. 2020. Rotary club presentation of the experimental system/results of 2020 study. Marshall, MN. Oct 23rd 2020.

Learning Outcomes

10 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

20 Farmers changed or adopted a practice
5 New working collaborations
Project outcomes:

After evaluating squash and cucumbers grown on four different mulch treatments (silver reflective, white plastic, black plastic, bare ground) at two locations in 2019 and three locations in 2020, we found a significant effect of mulch treatment on yield of squash and cucumbers with black and silvery reflective mulch tending to yield significantly more fruit. However, greater densities of  squash bugs were found on the plastic mulch plots compared with bare ground.  These results suggest that in addition to aiding  in weed suppression, colored plastic mulches positively impact crop yield of cucurbits, but also may result in greater squash bug populations.  This information can aid in the decision making for growers to invest in the cost of plastic mulch for their cucurbit production.    

In another experiment, the squash bug parasioid, Gryon pennsylvanicum was reared in Blacksburg Virginia and augmentative releases were made on two farms in eastern Virginia, while two nearby farms included as non-release controls.  Parasitism of squash bug egg masses was increased significantly at the release sites.  While more data are needed, these results are promising for the potential to enhance biological control of squash bug.


In 2021, we will embark on objective 2 of the grant where we will be assessing the effects of living mulch between the row beds of squash.  The living mulch will include a mix of teff grass to suppress weeds and buckwheat and red clover to provide floral resources for natural enemies and pollinators.  The experiment will be conducted in Georgia, North Carolina, Minnesota, and two locations in Virginia.  We will assess the effects of the living mulch treatment with and without insecticide applications on populations of insect pests, natural enemies, and pollinators.  Yield of squash will also be assessed.  

Information Products

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.