Management of Arthropod Pests of Vegetables and Fruit

NON-TECHNICAL SUMMARY: Although there has been an increased interest among American consumers in organic produce, there has been an even greater interest in locally produced produce. Much of this interest is because of food safety concerns, enhanced food quality, local economic development, and issues related to shipping produce long distances. One of the problems growers face in the Midwest is that the growing season is cut short by harsh winter weather that precludes crop production. One way of overcoming this problem is to grow fruits and vegetables within unheated high tunnels. High tunnels provide a practical way to extend the growing season across much of the North Central region. Research and demonstration projects in other states and the experience of those growers who have used high tunnels for vegetable production in Indiana and surrounding states have shown that the growing season can be extended, sometimes dramatically, for many vegetable crops. Interest in this technology is high, in Indiana as well as throughout the region. One aspect of high tunnel production that has not been systematically investigated is pest management. Experience and limited research tell us that some problems may be reduced (i.e. early blight on tomatoes) and some increased (i.e. aphids in peppers), but we do not have comprehensive information about the pest complex in high tunnel vegetables. Effective management systems are available for most field-grown vegetables, but no systems have been designed for use within high tunnels. This is a serious constraint to the profitability and sustainability of high tunnel production. The corn earworm, has been identified as one of the most important insect pests of sweet corn, requiring multiple sprays of insecticide to achieve desired levels of control. Corn earworms damage sweet corn by feeding on the kernels. This feeding damage results in yield reductions in sweet corn grown for processing, as well as in field corn, seed corn, and popcorn. Damaged kernels and/or the presence of an earworm larva in an ear of fresh market sweet corn usually make that ear unmarketable. Average losses from corn earworms are estimated to be 3.6% in sweet corn for processing and 12% in fresh market sweet corn. The most common sampling method for earworms is to use sex pheromone lures to determine the need for insecticide treatments. A widely used decision rule is to apply insecticides when the sweet corn crop is in a vulnerable stage (green silks present) and ten or more males per night are being caught in the pheromone trap. The threshold of 10 moths per trap per night is considered a nominal threshold because it was developed based on the experience of pest managers rather than empirical data. Even though this nominal threshold has been widely adopted and has resulted in considerable reduction in pesticide use when employed, there are a number of knowledge gaps between the capture of male moths in pheromone traps and ear damage that, if better understood, could result in refinement of the action threshold. <P>

APPROACH: <BR> 1. Six high tunnels purchased with Mary Rice grant funds will be installed in spring, 2009 at the Meig's Research Farm. Various vegetables (tomatoes, peppers, cucumbers) and small fruit (strawberries and raspberries) will be grown in the tunnels along with comparison plots outside the tunnels. During 2009 and 2010, the crops will be sampled routinely throughout the growing season for arthropod pests and natural enemies. Previous observations have shown that aphids and spider mites tend to be more serious problems inside high tunnels while other pests such as beetles and caterpillars tend to be less serious within the tunnels.<BR>2. A study funded by a NCIPM grant will be initiated in 2009 to improve the ability to predict damage from corn earworms on sweet corn. Multiple plantings (up to 10 per year) of two varieties of sweet corn with different maturity dates will be made at 4 locations, Lafayette and Vincennes, IN and Urbana and Collinsville, IL. The project will last for two years. For each planting, 500 plants will have their primary ears bagged just prior to silking. For each of the ten nights of the silking period, bags will be removed from 50 ears to allow moths to lay eggs on the silks. Half of the 50 ears will have their silks removed and eggs counted. The remaining 25 ears will be rebagged for the remainder of the silking period and damage measured at harvest. Pheromone, blacklight and food bait traps will be maintained at each location and checked daily. Weather variables such as temperature, rainfall, wind speed, and relative humidity will be measured. Crop phenology and the phenology of surrounding corn crops will also be noted. Regression models will be constructed to determine the ability of each trap type to predict egg laying and subsequent oviposition. <BR>3. A large block (10 acres) of land at the Meig's Research Farm will be designated for organic research. A 3-4 year rotation of vegetables (fresh market tomatoes, peppers, and cucubits) and grain (corn and soybean) or forage (alfalfa) crops will be initiated. Studies will evaluate changes in soils, insect, disease, and weed pressure, and crop yield and quality during conversion to organic production.4. Conventional insecticides will be compared with new reduced risk insecticides for efficacy against pest species as well as the effects on beneficial arthropods for several different fruit and vegetable crops in small plots at Purdue Ag. Centers. A new insecticide with a novel mode of action from DuPont (rynaxypyr) will be evaluated on apples, sweet corn, and cucurbit crops. With the impending removal of Furadan from the market, several products will be evaluated on muskmelons for control of seedcorn maggots and striped cucumber beetles. The potential development of resistance among corn earworm populations necessitates the evaluation of several new products with new modes of action.