Row Cover Use Methods for Cucurbit Pest and Pollinator Management

View the project final report

• 2016 annual report

Commodities

• Vegetables: cucurbits

Practices

• Education and Training: on-farm/ranch research
• Pest Management: cultural control, integrated pest management, prevention, row covers (for pests)

Vegetable production is an important component of various types of farms in Oklahoma and surrounding states of the central plains region of the US. For many of these farm operators, sustainability depends on being able to consistently produce a marketable quality crop in order to have continuity in marking venues. For some vegetables, such as tomato, it is not possible to produce consistently from year to year due to extreme environmental conditions that periodically interfere with the physiology of the crop. In contrast, for cucurbit vegetables, our long, warm growing season makes this a crop enterprise that is physiologically well adapted to the region and these vegetables, including summer squash, winter squash, pumpkin, cucumber, cantaloupe and watermelon may be found in the field for nearly 8 months of the year. Although well adapted to the region, cucurbit production is not free of production risks and one important general problem is the hazards posed by insect pests. Major insect pests include squash bug, several species of cucumber beetle, aphids, squash vine borer and several Lepidoptera pests (Riley et al, 1998).  All of these insects have potential to cause severe or complete crop loss if left uncontrolled and effective management is critical for successful production and usually involves consideration of several potentially damaging insect pests (Bolin and Brandenberger, 2001). For some of these pests, effective control measures are available and typically involve the use of synthetic insecticide applications. For others, control measures can be either difficult to employ or of limited efficacy. For example, summer squash production for commercial markets is greatly limited by the difficulty of controlling squash bug without injuring honeybee pollinators with insecticides. Virus infections can severely injure cucurbit crops by reducing yield and rendering fruits unmarketable. The only practical means of control of this disease is to use exclusion techniques that prevent aphids that vector these virus diseases obtaining access to the crops. Thus, the development of effective management techniques for cucurbit crops would add to the sustainability of farms in the region by improving the predictability of being able to produce yields of marketable quality cucurbits, thereby enabling growers to be able to consistently produce a product supply that they can, in turn, use to develop market opportunities.

Small scale vegetable production for local sales is on the increase (Hardesty, 2008) and this seems to be the trend in Oklahoma. For example, over 50 small farmers in Oklahoma have recently been introduced to vegetable production and marketing through a program of the Oklahoma Department of Agriculture Food and Forestry (http://www.ag.ok.gov/mktdev/plasticulture.htm).  In Oklahoma, small scale vegetable production is moving closer to urban environments which creates new challenges for insect pest management. For example, non-traditional producers are often interested in reduced pesticide use and the use of organic approved practices. Thus, there is a need for alternative pest management practices that are suitable for use in vegetable production in the urban environment.

Production systems employing a combination of planting beds elevated above grade in conjunction with bed coverings (mulch) are beneficial for vegetables in this region. Benefits of such systems may include weed control, improved soil conditions for plant growth, produce sanitation and reduced incidence of plant diseases (Shrefler and Brandenberger, 2014). The additional component of row covers provides insect exclusion (Cartwright et al., 1990). While reference is often found to the use of this technique, it is less common to find detailed instruction of application and removal procedures.  Previous studies in Oklahoma showed that timing of row cover removal can have a significant impact on squash plant survival and the productivity of marketable fruit. Specifically, delaying row cover removal for two weeks after squash begins to set female flowers allows plants to become larger before squash bugs colonize plants and, for early season plantings, this resulted in greater yields compared to plants for which the covers were removed immediately following first female flower set. These results showed that delayed removal of row covers can greatly increase squash yields. However, once covers are removed the crop is exposed to insect pest infestation, which is typically the cause of cessation of fruit production. A possible solution to the overall problem would be to find ways to exclude insect pests that does not exclude honeybees and other pollinators. Because cucurbit crop pollination occurs during morning hours, generally from sunrise until mid-morning, allowing access to pollinators by removing covers for only for that period might allow for pollination to occur without providing prolonged access to insect pests.

Field trials were conducted to evaluate row cover use and management for the exclusion of insect pests in cucurbit vegetable crops. The practices that are being evaluated are designed to address the exclusion of insect pests from the crop as well as the need for pollinator access to the crop.

Project objectives are:

1. Evaluate possible row cover management practices to determine their efficacy and practicality of implementation.
2. Increase grower awareness of alternative insect pest management practices for cucurbit crops.
3. Communicate to growers the concepts being employed in the practices used in this research, including both the insect pest management and pollinator aspects.

Two general row cover management were assessed and compared:

1. Cover crops with insect excluding fabric until the initiation of female flower production and then removing these at some point in time afterwards
2. Cover crops with insect excluding fabric until the time of female flower production and then, on a daily basis, open and close the covers during morning hours.