Determining an economic injury level for the persea mite,Oligonychus perseae,a new pest of avocado in Israel |
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Authors: | Yonatan Maoz Shira Gal Miriam Zilberstein Yoanatan Izhar Victor Alchanatis Moshe Coll Eric Palevsky |
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Institution: | 1. Department of Entomology, Institute of Plant Protection, Volcani Agricultural Research Organization (ARO), Newe‐Ya’ar Research Center, POB 1021, Ramat Yishay, 30095, Israel;2. Bio‐Fly, Kibbutz Sdeh Eliyahu, Beit Shean Valley, 10810, Israel;3. Western Galilee R&D, MP Oshrat, 25212, Israel;4. Institute of Agricultural Engineering, Volcani ARO, Volcani Center, POB 6, Bet Dagan, 50250, Israel;5. Department of Entomology, The Hebrew University of Jerusalem, POB 12, Rehovot 76100, Israel |
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Abstract: | The persea mite, Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), a pest of avocado, was first discovered in Israel in the autumn of 2001. It has since spread to most avocado growing areas in Israel. To establish an economic injury level (EIL), based on the percentage of leaf area damaged (PLAD), we conducted an extensive field study. For three consecutive seasons we created distinct pest infestation levels on the Hass avocado cv., by applying acaricides (spirodiclofen and abamectin) at 50, 100, and 250 mites per leaf levels, along with non‐sprayed controls in a replicated block design. At harvest time we evaluated the level of leaf damage and fruit yields across treatments. In two out of the 3 years, trees sprayed at 50 and 100 mites per leaf levels had similar PLAD values, differing from trees treated at the 250 mites per leaf level and the non‐treated control, the latter pair also being similar. Over the 3 years, mean yield attained at the two higher infestation levels was reduced by 20% in comparison to the mean yields recorded for plots sprayed at the lower thresholds. Accordingly, we suggest that scouts adopt an action threshold (AT) of 50–100 mites per leaf. Future research is needed to refine this AT. Mean annual cumulative mite days (CMDs) of the two higher levels was ca. 13500 ± 700 per leaf. Using the linear regression equation PLAD = 0.0009CMDs + 2.42, describing leaf damage as a function of CMDs, we estimated an EIL of ca. 15 PLAD. |
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Keywords: | action threshold damage threshold cumulative mite days percent leaf area damage yield Acari Tetranychidae |
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