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Illinois Fruit and Vegetable News:A Newsletter for Commercial Growers of Fruit and Vegetable Crops Vol. 16, No. 11, August 19, 2010 |
"We are what we repeatedly do. Excellence, then, is not an act, but a habit." --Aristotle Address any questions or comments regarding this newsletter to the individual authors listed after each article or to its editor, Rick Weinzierl, 217-333-6651, weinzier@uiuc.edu. To receive email notification of new postings of this newsletter, call or write the same number or address. In This Issue:Regional Updates (from Maurice Ogutu) Fruit Production and Pest Management (San Jose scale on apples, mealybug on peaches) Vegetable Production and Pest Management ("Lep" pressure is intense in sweet corn) University of Illinois Extension Specialists in Fruit & Vegetable Production & Pest Management Upcoming Programs
Regional UpdatesIn the northern region, the last two weeks have seen some extremely hot weather and a few pleasant days with highs in the 70s. Despite heavy rains in some locations, soil moisture content is very low in many parts of the region and irrigation equipment is in use on many farms. Cover sprays continue in apples to control scab and summer diseases such as sooty blotch and flyspeck. Japanese beetle remains a target of insecticides, but numbers have declined. Calcium sprays also remain important in apples. Some U-pick orchards are open, with customers picking early maturing apple varieties such as Redfree, William's Pride, Sansa, Gravenstein, and Zestar. Peaches and pears are also ready for picking in some orchards. Grapes are changing color, so it is time to cover the vines with nets and use other bird scaring devices. Adequate soil moisture is very crucial in orchards during this period when fruits are sizing, so irrigating tree fruits will be beneficial if systems are in place to get the job done. Vegetable harvesting continues at full speed. Sun scald has been very common on fruiting vegetables such as tomatoes and peppers, and early blight has been reported on tomato fruits and leaves. Western corn rootworm beetles and cucumber beetles are common on vine crop leaves and blossoms, and various aphids are present in a range of vegetable crops. In pumpkins, squash and muskmelons, I've seen powdery mildew on leaves, and I have received reports of diamond back moth, cabbage looper, and imported cabbage worm on cabbages. I also observed black rot on cabbage, and bacterial spot and cercospora leaf spot have been reported on peppers. Maurice Ogutu (708-352-0109; Ogutu@illinois.edu) Notes from Chris DollChris is somewhat out of commission for a bit following hip replacement surgery about 10 days ago. For all who would like to wish him well, his address is 4681 Drda Lane, Edwardsville, IL 62025-5801. We all look forward to his return to writing for us as soon as he's up to it. Fruit Production and Pest ManagementSan Jose Scale on ApplesI have had a couple of calls about San Jose scale on apples causing discoloration on the fruit itself. Although we often stress the importance of prebloom oil applications to suffocate overwintering scales and specific products in sprays around 3 to 5 weeks after bloom to kill first generation crawlers, an additional generation develops later in the summer and is the cause of problems occurring now.
Although Esteem is effective against crawlers earlier in the season, the required preharvest interval (PHI) for Esteem in apples is 45 days, so by now it is not an option in most blocks. Alternatives where crawlers are still active now include diazinon (21-day PHI), Assail (7-day PHI), and Centaur (14 days). See the 2010 Midwest Tree Fruit Spray Guide for rates and restrictions. Mealybug on PeachesEarlier this month I responded to a report of an infestation of insects that at first look resembled, at least in general, woolly apple aphid … but on peaches. A closer look revealed that the culprits were mealybugs. Mealybugs are somewhat related to aphids (both groups are in the insect order formerly known as Homoptera – the aphids, scales, mealybugs, leafhoppers, etc.), but only adult males (not females) are winged, so the gender that lays eggs (or in some species gives birth to live young) is not able to disperse over very great distances. Mealybugs are not common pests on most outdoor crops in Illinois or elsewhere in the Midwest, and I have never seen mealybugs on peaches (or apples) in Illinois in the 20 years I've worked on fruit insects. Comstock mealybug, a somewhat common pest of apples in the northeast, is reported to infest peaches and its distribution is reported to include the Ohio and Mississippi River valleys. Grape mealybug also is known to infest peaches. I have not yet confirmed the species identification of the mealybugs in this infestation. The grower had made an insecticide application that must have been pretty effective, and nearly all the insects recovered from the fruit and shoots were dead first-stage nymphs (immatures). If anyone else finds infestations of mealybugs on peaches or apples, please contact me so that I can collect samples for identification before insecticides are applied. Rick Weinzierl (217-333-6651; weinzier@uiuc.edu)
Vegetable Production and Pest Management"Lep" Pressure is Intense in Sweet CornCorn earworm counts from pheromone traps have been VERY high in many parts of the state over the last few weeks. At Urbana, counts have topped 450 per night on two occasions recently; counts have exceeded 200 per night in southwestern Illinois; and counts from far northern Illinois have been greater than 100 per night. Keep in mind that our least conservative estimates of a threshold for control in sweet corn is never greater than 10 moths per trap per night, so these numbers suggest very high levels of damage will occur in untreated fields. The potential for damage is aggravated by the fact that silks are brown and dried in field corn throughout the state, so egg-laying by corn earworm females will be concentrated in sweet corn with fresh silk. Fall armyworm is also active, so now is not the time to stretch spray intervals or fail to make any applications. As noted in the previous issue of this newsletter, pyrethroids such as Warrior, Brigade, Baythroid, and Mustang-Max generally give good control of these insects; Coragen and Radiant also have been effective. Repeated sprays at 2- to 3-day intervals usually are required. See the Midwest Vegetable Production Guide and product labels for rates and restrictions for specific insecticides. For organic growers, Entrust (OMRI-approved) is much more effective against these insects than the other insecticides approved for use in certified organic production systems. Rick Weinzierl (217-333-6651; weinzier@uiuc.edu) University of Illinois Extension Specialists in Fruit and Vegetable Production & Pest Management
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 Integrated Pest Management College of Agricultural, Consumer and Environmental Sciences Crop Sciences | Entomology Natural Resources & Environmental Sciences Illinois Natural History Survey |
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