Integrated Pest Management for Two Red Raspberry Pests Utilizing UV-Blocking High Tunnel Plastic Films
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- Open Access.
- In the early 2000s, red raspberry crops in the Northeast United States were increasingly produced in high tunnels. High tunnels have potential to decrease the amount of pesticides used to produce raspberries; fungicides can be unnecessary and many arthropod pests are successfully controlled through natural enemies in the tunnels. However, insecticides are still the primary tool that growers use to protect raspberry crops from pests like Japanese beetles and spotted wing drosophila (SWD). Using insecticides for SWD control is especially problematic because the short residual activity of treatments requires growers to make many applications over the season putting high selection pressure on SWD for resistance. Controlling SWD is so difficult and costly that adoption of high tunnels for red raspberry has slowed in Pennsylvania.While Japanese beetles have only a single generation per year, and resistance is less likely, their control also often relies on very few chemicals. In both cases, sprays present risks to beneficials that are important for the ecosystem of the tunnel. Many insect pests are reduced in greenhouses using UVA-blocking plastic films. We investigated the effects of plastics that transmit different amounts of ultraviolet light on Japanese beetles and SWD. Many insects are sensitive to light in the UVA range and use it for navigation, and high tunnel plastics that block varying amounts of UV radiation are increasingly available. Combining deterrents and attractants in a push pull system has been a successful IPM strategy in many crops. Attracticidal spheres, red balls containing sugar and a toxicant, are effective for reducing SWD populations in trials of field-grown raspberries. Shortened harvest interval has decreased infestation in tunnels. We hypothesized that combining the pushes of UV-blocking plastic and daily harvest with the pull of the attracticidal spheres could create an effective non-spray control program for SWD in high tunnels. We grew two primocane-bearing red raspberry cultivars, Polka and Josephine, under six different covering treatments in 2016 and 2017. Five were plastics which blocked the ultraviolet range to varying degrees, and one treatment had no plastic covering. In 2016 Japanese beetles were counted and removed daily from the plants by hand. In 2017 beetles were removed by hand every 5 days. In both years SWD populations were monitored using apple cider vinegar traps which were collected on a weekly basis throughout the harvest season. Foliage temperature was measured in each tunnel twice in 2017 with an infrared thermometer. Spectral transmittance characteristics of the plastics were measured with a spectroradiometer in 2015 or 2016 and 2018. Mean beetle counts by date and for the whole season were compared for the plastics and cultivars. Japanese beetle numbers were significantly higher in the no plastic treatment than under all plastic treatments. The plastic that when new blocked >90% of the UV range in our measurements had significantly lower beetle populations while the plastics which blocked the least UV had significantly higher beetle counts. It appears that using a UV-blocking plastic can reduce Japanese beetle aggregation and feeding damage on raspberries. This could benefit growers by eliminating the cost of purchasing and applying insecticides, and also decrease the exposure risk for to non-target organisms.Spotted wing drosophila trap numbers were significantly impacted by whether the raspberry plants were grown inside tunnels. Compared to the outside treatment, all plastics had lower numbers in 2016 and higher numbers in 2017, but plastics did not significantly differ. Given these results, it seems unlikely that spotted wing drosophila is affected by plastics with different transmittances. This was supported by bioassays conducted in laboratory and field cage settings in 2018 where there was no difference in foraging behavior between UV-blocking and UV-transmitting plastics, and a control treatment. In 2018 we also grew Josephine raspberries in tunnels under two covering treatments, a UV-blocking plastic and a UV-transmitting plastic. We tested combinations of these plastics, attracticidal spheres, and different harvest intervals. Fruit was harvested for two twelve-day periods during which we measured the marketable weight, total weight, and average fruit weight, and calculated the percentage of marketable fruit. Subsamples of fruit were submitted to saline floats to extract larvae and evaluate infestation. There were no significant differences between plastics in the amount or percentage of marketable yield, fruit weight, or infestation of marketable fruit. Daily harvest significantly increased total and marketable yield compared with a Monday, Wednesday, Friday harvest schedule. Daily harvest and spheres significantly decreased the infestation of marketable fruit. In fruit that was considered unmarketable, UV-transmitting plastics also significantly reduced infestation. This suggests that a daily harvest schedule can increase marketable yields for growers and using attracticidal spheres can reduce infestation. Plastic seems unlikely to make a difference in the infestation of marketable fruit, and many growers already use UV-transmitting plastics. Overall, our research shows that combining a daily harvest interval with the application of attracticidal spheres can significantly reduce infestation and yield losses. Adoption of these control tactics would greatly reduce the risk to non-target and beneficial organisms in tunnels, the cost to growers in sprays, and the risk of resistance development by SWD.
- Dissertation Note:
- M.S. Pennsylvania State University 2018.
- Technical Details:
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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