Vegetable and Berry Crop Insect and Disease Update, 25 August 2016

By Alan Eaton, George Hamilton, Cheryl Smith & Becky Sideman, UNH Extension

Sweet corn: Corn earworm and Fall armyworm numbers have jumped this week, so sweet corn growers in much of the state need to keep fresh silking corn protected. You can view recent insect trap catches (updated Sundays) at http://extension.unh.edu/IPM-Trapping.

Squash and pumpkins: We are starting to see Squash vine borer numbers going up (some southern NH sites), at a time when they usually go down. This appears to be the start of a second generation, which sometimes occurs in New Hampshire. When it does, the fruit are significantly attacked, especially hard squash and pumpkins in the warmer parts of the state.

Cucumber, Cantaloupes, Acorn & Summer Squash: Cucurbit downy mildew has been confirmed in Franklin County, Mass. Commercial growers of these crops that are located in Cheshire County should be applying protectant fungicides if they intend to do so, and those nearest the MA border may want to switch to fungicides specific to downy mildews (oomycetes). You can read more about identifying this pathogen here. The New England Vegetable Management Guide is the best resource for current fungicide recommendations, specific to individual crops.

Potatoes and Tomatoes: Growers have been asking me all summer about the status of Late Blight. The good part of the very hot weather and drought we’ve been experiencing is that it does not favor the spread of late blight! The closest late blight is now in Aroostook county, Maine, but this should NOT be cause for alarm. This is likely to move here ONLY in the case of prolonged cloudy weather and storm systems moving in from the Northeast. To our south and west, it is in Maryland, but no closer. You can keep an eye on the map yourself if you like! We will keep you posted if it gets any closer.

Fall Berries: Numbers of Spotted Wing Drosophila (SWD) flies are climbing around the state, on the verge of exploding at some sites. Nearly all of our southern trapping sites are now over the recommended threshold for protecting ripening fruit. Berry growers (especially blueberries, fall raspberries, blackberries) should be spraying ripening fruit regularly to prevent infestations. At this point, growers should follow a 7-day spray schedule to provide adequate protection. A list of registered pesticides for SWD control is listed here.

 

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