August 1998 // Volume 36 // Number 4 // Feature Articles // 4FEA3

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Integrated Pest Management in Cucurbit Crops in South-Central USA: Pest Status, Attitudes toward IPM and a Plan for Implementation

USDA Cooperative Agreement Project G-8438 was initiated in 1995 to develop a plan to implement IPM on cucurbit crops in South-Central USA using Texas and Oklahoma as representative states. Through this project, the current status of cucurbit IPM was surveyed in terms of implementation and research. Constraints to an advanced IPM system were identified in facilitated workshops and research, Extension, and education priorities for implementing IPM in cucurbit crops were developed. From the survey it appeared that IPM was fairly well understood by workshop participants. The main tools for management of pests included application of pesticides, disease resistance incorporated into cultivars, and cultural practices such as manipulating planting dates and field rotation. Workshops (consisting of a comprehensive educational program along with facilitated discussions and a short survey) were well received and provided an opportunity for assessment of current IPM programs by representative IPM users in cucurbit crops. Research and Extension continue to be critical for IPM implementation.

D. G. Riley
Assistant Professor
Coastal Plain Experiment Station
University of Georgia
Tifton, Georgia
Internet address:

J. V. Edelson
Oklahoma State University
Lane, Oklahoma
Internet address:

R. E. Roberts
Texas A&M University
Lubbock, Texas

N. Roe
Assistant Professor
Texas A&M University
Stephenville, Texas

M. E. Miller
Texas A&M University
Weslaco, Texas

G. Cuperus
Oklahoma State University
Department of Entomology
Stillwater, Oklahoma

J. Anciso
Extension Agent
Texas A&M University
Edinburg, Texas


Cucurbits are an important part of the fresh market vegetable crops in the USA comprising approximately 9% of all fresh vegetable shipments in 1992 (USDA Agricultural Statistics 1993). Cucurbit fruit such as pickling cucumber, pumpkin, and squash, are also important processed or frozen commodities. Watermelon, cantaloupe, honeydew melon, cucumber, squash, and pumpkin are grown throughout the south central region of the U.S. from south Texas through Oklahoma. It is estimated that over 100,000 acres for the crop complex as a whole are produced in Texas and Oklahoma.

The fruit is primarily channeled through the fresh market and through processors for pickles and frozen goods. The pest complex attacking these crops in these areas can result in severe yield losses. Consumer demands for unblemished produce in the fresh market coupled with the United States Department of Agriculture (USDA) and Food and Drug Administration (FDA) regulations for the processor market dictate that cucurbit fruit be blemish free and of standard size and color. Because of this, pesticide usage has remained high for these crops and adoption of integrated pest management (IPM) practices slow because of the perceived risks to production.

A fundamental aspect of IPM affecting growers, government regulators, and consumers alike is the concept of risk. An important risk to growers that rely heavily on pesticides is the development of resistance to pesticides that can greatly affect production economics and pesticide use patterns.

There are also the real and perceived risks to human health. These include potential chronic health effects from pesticides in diet, exposure to acute toxicity by agricultural workers and handlers that deal with pesticides, and indirect exposure through feeding of treated plant material to livestock. Risks to environmental quality can include non-target effects of pesticides, effects of pesticides on the severity of other pests, reduction in the abundance of fungal parasites of the invertebrate pest (e.g., EBDC fungicides increasing aphids), toxicity to aquatic vertebrates, and contamination of groundwater (soil-mobile fungicides, e.g., metalaxyl). A basic assumption of the proponents of IPM is that IPM can reduce these risks.

In 1993, the USDA, Environmental Protection Agency (EPA), and FDA entered into an agreement to develop and implement IPM on 75 percent of the total crop acreage in the United States by the year 2000. In 1994 the USDA Cooperative State Research, Education, and Extension Service (CSREES) began with an initiative focusing on developing plans for implementing IPM on specific agricultural commodities. Scientists and specialists with Oklahoma State University, USDA-SCARL and Texas A&M University submitted a planning grant proposal to implement IPM on cucurbit crops in Oklahoma and Texas that was funded for one year.

The goal of this planning grant, USDA Cooperative Agreement Project G-8438, was to develop a plan to implement improved IPM methods on cucurbit crops (cantaloupe, watermelon, cucumber, squash, pumpkin, etc.) in south-central USA. Three specific objectives of this project were to: (a) describe the current status of IPM in terms of implementation and research at IPM workshops in Texas and Oklahoma, (b) allow IPM practitioners (workshop participants) to define the constraints to an advanced IPM system, and (c) identify research, Extension and education priorities for implementing IPM in cucurbit crops.

Materials and Methods

A series of cucurbit IPM workshops were held in Oklahoma and Texas in 1995-1996 to promote cucurbit IPM and to survey growers, pest consultants, government agencies, and related agricultural industries on their needs for increasing the implementation of IPM. Major pests, such as arthropods (e.g., foliar aphids, whiteflies, squash bugs, cucumber beetles, etc.), plant pathogens, weeds, and others were identified and ranked by participants of the workshops without providing choices or leading information so that an unbiased list of pests could be generated.

Also, participants were asked candid questions about their perception of IPM and the role of government agencies in IPM implementation. The workshop conferences were held at sites close to representative production areas within the south central region in Texas and Oklahoma.

The survey at the workshops was to evaluate pest management in various cucurbit production areas in terms of levels of implementation of IPM and specific research and education needs to increase the level of implementation. A survey was circulated, time allowed for answering, and then responses were discussed, using one person to facilitate the discussion. In Oklahoma, a facilitator reviewed the survey results with participants, who then voted on the importance of the various topics identified. After the discussion session, seminars on current cucurbit pest management and crop production research were provided for the participants along with educational materials (books, bulletins, leaflets, etc.).

In Texas, a series of facilitated workshops at growers' meetings surveyed responses to the following five questions. These were as follows: (a) What are the three most manageable and the three most unmanageable pest problems in cucurbit crops? (b) What are IPM practices (give one example) and do you think that the use of this practice improves the image that U.S. consumers have of the agricultural industry? (c) Do you use or endorse IPM and do you think it increases or decreases production risks? (d) What are the biggest constraints on IPM? (e) What is the most important thing that agencies (Experiment Station, Extension Service, Department of Agriculture) can do to improve pest management in cucurbits?

For each meeting, a brief introduction was included to give an overview of the project and the survey was conducted before discussing each question individually to avoid influencing responses. A total of 168 participants were surveyed in Texas representing growers, pest consultants, pesticide industry representatives, and agricultural government agencies.

The Oklahoma surveys were also conducted in a series of facilitated workshops at growers' meetings during the winter of 1995- 1996. A facilitator then moderated the meeting and presented a series of three survey questions to the grower and industry audience. The three questions asked were: (a) Do you use IPM? (b) What are the constraints to adopting IPM? (c) What do you want universities and USDA to do to aid in pest management?

The first workshop was conducted in an open forum in the Tulsa Horticulture Industry Show, January 1996 (ca. 45 participants, including growers, applicators, and consultants). The second was at the Vegetable Production Meeting at Hydro (ca. 20 growers, consultants, and agricultural industry representatives) and the third was at a grower meeting at Rush Springs (13 growers). The responses were recorded and after all response from the audience was complete, each participant was asked to 'vote' on the most important issues (responses). Based on counts of votes, the top priorities were determined and ranked.

A total of 168 participants were surveyed in Texas and 78 in Oklahoma representing growers, pest consultants, pesticide industry representatives, and agricultural government agencies. Following all of the workshops, selected team members reviewed findings and summarized the data.


The pest complex for the cucurbit crops could be divided into four major categories: arthropods, diseases, weeds, and vertebrate pests. The major pests of cucurbit crops in south central USA were identified by researchers and Extension specialists in the planning grant proposal by category in Table 1. The cucurbit pests identified at the workshops were similar, but one major difference was that researchers and Extensionists attempted to identify all possible pests for this region represented by their discipline, where as workshop participants simply identified one or two pests of immediate concern (Table 2).

Table 1
Researcher/Extensionist Identified Pest Problems
In Cucurbit Crops in South-Central USA

1. ARTHROPODS foliar aphids (melon aphid, cowpea aphid), whiteflies, squash bug, cucumber beetles (various species), leafminers, leafhoppers, spider mites, thrips, rind-worm complex (melonworm, pickleworm, cabbage looper, corn earworm, armyworms), seedcorn maggot, squash vine borer, ants, darkling ground beetles, false chinch bugs, field crickets, grasshoppers, lygus bugs, leafrollers, saltmarsh caterpillar, flea beetles, flea hoppers, japanese beetles, stink bugs, cutworms, wireworms.
2. DISEASES vine declines (monosporascus root rot, charcoal rot, gummy stem blight, fusarium wilt, yellow vine), downy mildew, insect-transmitted viruses (watermelon mosaic virus, papaya ringspot virus, zucchini yellow mosaic virus, cucumber mosaic virus, squash leaf curl virus), bacterial wilt of cucurbits, bacterial fruit blotch, powdery mildew, anthracnose, cercospera leafspot, alternaria leafspot, Phytophthera spp. rot, angular leaf spot, choanephora wet-rot, fusarium rind rot, reniform nematodes, root knot nematodes.
3. WEEDS pigweed (Amaranthus species), various grass species, pie melon, and nutsedges (particularly in plasticulture) and many others (not fully represented).
4. VERTEBRATES various bird and rodent species that feed on seeds and seedlings, as well as birds, coyotes, raccoons and opossums that feed on fruit and deer that feed on foliage.

The results of the workshop surveys identified and ranked the most important pests in the view of the participants at the workshops. Table 2 represents the combined response of 168 workshop participants in Texas to the question, "What are the three most manageable and the three most unmanageable pest problems in cucurbit crops?". The participants included agricultural producers (small farms to large corporate farms), packers and processors, crop consultants, pesticide industry representatives, federal researchers, state researchers, and Extension specialists. From the 626 individual responses, 28% were only identified to categories, such as insects, fungi, etc., that were too general to make any logical pest management decision. In addition, 3% of the respondents misidentified a pest problem, for example, "rust" or pollination as a pest. This suggested that there is a serious need for better pest identification and training so that at least the pest species and disease agents are properly identified among the IPM team members.

It was expected that there would be some respondents that would not classify the pests as manageable or not, but the resulting 36% unclassified pests was higher than expected. This could reflect an inability or unwillingness to properly categorize pests in terms of their manageability, which suggests that better pest identification/classification training is needed. On the other hand, the responses did clearly point out the pest categories that most occupy the IPM team members attention (Table 2). These were: (a) insects (341 responses, 54%), (b) fungi (129, 21%), (c) weeds (52, 8%), (d) virus (25, 4%), and mammals (23, 4%). Interestingly, government personnel was indicated as a pest in a few responses.

Table 2
Participant-Identified Cucurbit Crop Pests
(most manageable and unmanageable, or unclassified)
Indicated as Number of Responses per Category
Based on 168 Total Respondents in Texas

Pest Type Pest Classifications
Manageable Unmanagable Unclassified Total
Insects (general) 13 16 35 64
aphids 18 25 32 75
melon/pickle worms 30 10 24 64
squash bug 4 13 27 44
whiteflies 3 16 12 41
cucumber beetles 13 5 16 34
stink bug 1 1 6 8
thrips 3 1 2 6
leafminer 0 0 3 3
ants 0 2 0 2
Fungi on foliage
and fruit (general)




downy mildew 13 5 4 22
anthracnose 3 5 5 13
melon blight 0 5 3 8
powdery mildew 2 0 5 7
gummy stem blight 1 2 0 3
"rust" or ID error 0 0 3 3
Fungi in soil




vine declines 0 23 6 29
Fusarium 2 6 0 8
Weeds (general) 10 4 4 18
grasses, sedges 26 4 4 34
Viruses (general) 4 18 3 25
Mammals: birds,
rodents, etc.




Bacterial wilt 1 10 3 14
Mites (general) 3 1 4 8
Other miscellaneous 4 3 1 8
Nematodes (general) 0 2 2 4

To further describe the current status of IPM in terms of implementation, the following question was asked in the workshop survey (Table 3). "What are IPM practices (give one example) and do you think that the use of this practice improves the image that U.S. Consumers have of the agricultural industry?" This double topic question was formulated to determine if the participants had a good grasp of the working of IPM and at the same time test their acceptance of these practices. Of the 168 respondents, 163 (97%) answered the first part of the question and only 71 (42%) answered the second part. One third of the responses to the first part had to do with the use of scouting and thresholds. Biological control, reduced pesticides, and cultural controls were also seen as important practices.

Table 3
Top Eight Examples of IPM Practices Given by Texas
Workshop Participants Ranked by Total Responses

Practices Total
Use of scouting and thresholds 53
Enhancement/release of beneficials 39
Reduced pesticide applications 25
Crop rotation/plowing residues 19
Bioengineered (Bt) plants 4
Information 4
Adjusting planting date 3
Host plant resistance 2

Other examples not listed in Table 2 were weed control, use of organic pesticides, spraying field perimeters, economic and environmental health, weed and bug control, reduce seed borne disease, airplane spraying, improved crop quality, and monitoring weather. In general, the results indicated that the participants had a reasonably good grasp of the what IPM involved. Of the 71 responses for the second part, 58 (82%) stated that IPM improved the image of the agricultural industry and 13 (18%) did not, but the overall lack of response to this question (only 44%) indicated that there was either an unwillingness to form an opinion or a lack of knowledge as to how IPM is viewed by the U.S. Consumers. Also, two respondents specifically stated that there was a lack of publicity about what IPM is and its benefits to the U.S. Consumers.

To determine if IPM was being used and whether or not its use was perceived as a risky proposition, the following question was asked. "Do you use or endorse IPM and do you think it increases or decreases production risks?" Surprisingly, 132 (89%) of the 148 respondents already used or endorsed the use of IPM, only 13 (9%) did not, while 3 (2%) were uncertain. Even though this was encouraging for IPM proponents the second part of the question revealed an important problem related to this enthusiastic response, i.e., perceived increase production risk to 37% of the respondents. Fifty-five (56%) of the 98 respondents to the second part of the question felt that IPM reduced production risks, but as long as this percentage does not rise, attaining the USDA targeted 75% use of IPM in cucurbit crops in the year 2000 is unlikely given that a majority of vegetable producers are risk aversive.

To evaluate constraints to the implementation of IPM the following question was asked (Table 4). "What are the biggest constraints on IPM?" The majority of the participants clearly indicated that information, and the integration of that information, was lacking for various pest problems. Also, specific IPM practices needed to be tailored to specific agricultural production locations.

Table 4
Top Eight Examples of Constraints to IPM Given
by Texas Workshop Participants Ranked by Total Responses

Constraints Total
Lack of information and integration 44
Time/dependable personnel for management 30
Problems hitting market/production windows 26
Environmental/weather 17
Economics/lack of money/cost of scouting 8
Lack of adequate thresholds 6
Lack of experience with IPM 5
Producer's resistance to change/fear of losing control 5

Constraints not listed in Table 3 were production risks (based on zero tolerance of pests), lack of available tools and chemical labeling, lack of qualified applicators and scouts, researcher's pesticide-oriented mentality, slow response to crisis situations, neighbors killing beneficial organisms, IPM is too much work and too crop specific (too much information), time lapse in control, staying on top of problems, organic production, synchronizing beneficial/damaging pest life cycles, soil management, and consultants protecting themselves. The importance of specific commodity markets and time constraints was evident in these responses.

The final question in the workshop survey was, "What is the most important thing that agencies (Experiment Station, Extension Service, Department of Agriculture) can do to improve pest management in cucurbits (Table 5)?" Again, the importance of IPM Extension, IPM research, and formal educational programs were highlighted by the responses. Also, there appeared to be a need for pest forecasting as well as providing current IPM information.

Table 5
Top Eight Examples of Agency Activities Suggested
by Texas Workshop Participants Ranked by Total Responses

Activities Total
Provide information through technology transfer
(extension, on-farm trials, printed information, etc.)
IPM research trials 42
Education and Conferences 13
Provide information on current pest situations/forecasts 7
Increase involvement in IR-4/product registration 6
Conduct more pesticide trials 6
Provide better thresholds 5
Rapid and accurate pest and disease diagnosis 3

The IR-4 program and product testing continued to be important as expected for a vegetable crop, since pesticide labeling (because of regulatory issues) and pesticide efficacy (because of pest resistance to chemical pesticides) are such dynamic issues. Other examples not listed in Table 4 were research on pathogens and their control, government inspection of commercial fields to check for problems, improved marketing, economic data on IPM, providing more money for agriculture, more tests on actual problems, increased industry support, increased yield quality and profit, development of spray schedules, agricultural weather forecasting, promotion of the use of natural insect enemies, work on the nutsedge problem, be involved with pest control, control all government expenditures, develop resistant varieties, and finally to let growers be aware of the agencies.

Table 6
Top Examples of Constraints to IPM Identified by
Hydro, Tulsa, and Rush Springs, OK Workshop
Participants, Respectively (total votes in right column)

Constraints identified at Hydro Total
Government regulations on pesticides constrain IPM 28
Government regulations interfere with IPM practices 27
Lack of information on economics of new IPM practices 20
Regulations are too tough for registering new pesticides 20
Constraints identified at Tulsa Total
Lack of validation for products, methods, and equipment. 15
Lack of knowledge of IPM tools. 11
Lack of crop protection and production workshops. 10
'Can't teach old dogs new tricks'. 10
Constraints identified at Rush Springs Total
Too many EPA regulations 9
Loss of pesticide registrations 5
Economics 4
Lack of better pesticides - more effective 4

The Oklahoma surveys were based on counts of votes and the top priorities were determined and ranked. In response to question #1, all growers with one exception indicated by show of hand that they believe that they use IPM on their farms. In a second workshop at Hydro at an annual vegetable grower meeting in February 1996, the priorities for research and extension were further examined with a similar facilitated survey. Again, all but one participant stated that they currently used IPM on their farms. Finally, at a workshop/grower meeting at Rush Springs all the respondents (13 growers) stated that they currently used IPM on their farms. The responses to questions #2 and #3 for all three workshops are listed in Tables 6 and 7, respectively.

Table 7
Top Examples of Priority Research and Education Needs
for IPM Implementation Programs Identified by Hydro, Tulsa,
and Rush Springs, OK Workshop Participants,
Respectively (total votes noted in right column)

Priority needs for research and education at Hydro Total
Pesticide trials/evaluations 55
Establish more and better pest thresholds 29
Research/education on beneficial insects and pollinators 25
Priority needs for research and education at Tulsa Total
Crop coefficients for irrigation needs. 13
Technology demonstrations. 12
Pest control (insects and disease). 11
Weed control. 9
Weather-driven plant and pest models (MESONET). 9
Third party registrations of pesticides. 8
Minor-use pesticide development and registration programs. 6
Priority needs for research
and education at Rush Springs

Economic thresholds for insects 7
Careless (pigweed) weed control 7
Aphid and squash bug control/management 6

Grower priority needs from Oklahoma-based producers were combined with those from Texas (producers, representatives of various agricultural industries, and government agencies) and a short list of priority needs were developed based on these responses. From Oklahoma and Texas the following were determined to be the top priorities for research and extension programs in the region:

First, agencies need to improve IPM delivery systems and technology demonstrations to get clear, user-friendly instruction to growers, agricultural consultants, and other users of IPM technology.

Secondly, more research is needed on specific problems, such as weed management, arthropod vectored virus control, soil borne pathogen management, foliar and fruit insect management, foliar and fruit pathogen management, beneficial insects (pest predators, pest parasites, and crop pollinators), etc., with priority ranking strongly differing between locations in Texas and Oklahoma.

Thirdly, more workshops and other formal educational conferences are desired for specific vegetables crops. They are seen as useful and concise mechanisms for providing information on IPM, particularly when printed materials on crop specific IPM were provided in the workshops. Crop-specific IPM books with color plates were highly desirable teaching materials at all of the workshops (e.g., "Cucurbit Production and Pest Management," OSU Circular E-853).

Fourthly, crop production issues, such as cultural practices, marketing windows, crop coefficients for irrigation, etc., need to be more integrated with pest management in any IPM programs that are developed for the producers for them to have any chance of adoption. This was one of the concerns that we attempted to address in the workshops by providing a comprehensive educational program along with the opportunity for questions and facilitated discussions.

Finally, assessment of IPM programs by representative IPM Team members, their economic viability, and annual re-evaluation for progress toward specified goals was seen as very important. The priorities identified in the workshop surveys attest to the importance of getting "outside" input.


The information presented in the workshops indicated that there is an abundance of IPM knowledge available, although certain serious pest problems continue to need research to find solutions. From the survey it appeared that IPM was fairly well understood by the workshop participants and was generally accepted as useful. The main tools for management of the pests included application of pesticides, disease resistance incorporated into cultivars, and cultural practices such as planting dates, field rotation and soil cultivation. Thus, it is likely that some integration of control tactics is already being used.

Disease resistance incorporated into cultivars was viewed as desirable, but is dependent upon commercial seed company interest and is driven by the economics of scale; for example, sufficient acreage and seed sales to warrant research and breeding. Use of planting dates and rotation is driven by economics; for example, market windows based on harvest dates and availability of suitable crop land with irrigation. The use of pesticides (a primary tool) is dependent upon availability of effective materials, regulations affecting the use of the materials on specific crops in specific regions and to a lesser extent on the impact on non-target organisms (i.e. honeybee pollinators), and human and environmental concerns (mammalian toxicity and handling, danger to aquatic organisms).

An effective integrated strategy for pest management is therefore affected by economics of production, government regulations, effective management strategies and education programs that transfer current research results to the industry. Considerable research has been conducted to develop IPM practices over the past decades either through the agricultural experiment station system, USDA/ARS and/or private agricultural industry. Production and pest management methods resulting from this work have been transferred into practice with varying degrees of success.

Based on informal discussions at the workshops, it was apparent that current pest management still relies heavily on chemical pesticide controls. However, workshop participants understood that there are limitations to this tactic including: (a) development of resistance to chemicals (for example, systemic fungicides like metalaxyl, benomyl, thiophonate-methyl, fosetyl Al, tridimefon); (b) the high costs associated with treatments in terms of both the application costs and environmental effects; (c) no clearly defined use recommendation based on economic thresholds; (d) lack of specifically needed products, such as fungicidal seed-treatments (no systemic fungicides currently labeled for seed treatment); (e) lack of advisories (forecasting systems:) for most foliar diseases; (f) lack of implementation of developed advisories; and (g) lack of systemic fungicides with eradicating properties (post-infection activity). Based on these discussions it was also apparent that other pest control tactics that need further evaluation and study included cultural controls, host plant resistance, and biological controls (antagonists, etc.).

There is a perceived lack of effective commercially- available biological control agents for management of pathogens. One participant commented that biological control of post-harvest diseases may be achieved using controlled environments. Field evaluations were viewed as necessary to determine the effectiveness of these same biocontrol agents in field conditions. Many participants felt that there is a lack of development of cross-protection to plant viruses in host plant resistance work. Systematic seed certification and seed health testing were also viewed as important in this area.

Regulatory control is another tactic that has been under utilized in pest management programs. This includes testing for seed and transplant health using certification/inspection methods. In the future the results of these surveys should be used to develop priorities for research and extension programs in the south-central region of the USA.