New Hampshire IPM Newsletter

Beetle on crop

The New Hampshire IPM Newsletter has been published by Alan Eaton, UNH Extension Entomologist, who retired in December. (For NH IPM Newsletter posts from years prior to 2018, see the NH Integrated Pest Management Newsletter Archives). 

For news related to IPM in Vegetable and Fruit Crops, please visit NH Vegetable & Fruit News. Published by our Vegetable & Fruit Team, this blog shares the latest news and research about vegetable and fruit production in the state and beyond.

Fruit Pest Hotline Transcripts

April 22, 2019

Degree day accumulation is 135 in Durham. Depending on the weather conditions at your site, you should be seeing some green tissue in apple orchards and therefore susceptibility to apple scab infection. Ascopore maturity is moderate – 4% - however rain events, temperature, and leaf wetness hours over the weekend provided ideal conditions for ascospore infection events. If you were not able to apply a preventative product, you might consider a fungicide with some kickback. Unless you are sure your risk is very low - meaning you had little scab last year and passed a PAD count last fall.  Consult the NE Tree Fruit guide for help selecting a product.

You might consider putting out white sticky traps to monitor for tarnished plant bugs entering the orchard. Hang them about knee height on the south side of trunks and above grass rather than bare ground as they will be moving from grass into trees. These piercing-sucking feeders will feed on developing fruit buds early in the season and cause cosmetic damage to fruit later in the season.

Now until pink would be a good time to scout apple orchards for the presence of winter moth or green pug moth larvae. This can be done by observing fruit buds for caterpillars or by tapping branches with fruit buds onto a white surface. Caterpillars will be knocked off and easier to see on the white surface of say – a white Frisbee? Presence of these sporadic pest species may trigger an insecticide treatment before bloom.

For blueberry – the recent wet weather means that any green tissue that may have emerged this week may be susceptible to mummy berry infection. If your blueberry plants are affected by any species of scale insect, a dormant or delayed-dormant oil spray may be appropriate. If you do have green tissue, make sure the oil product you are using specifically allows for delayed dormant applications.

It sounds like registration is full for the Tree Fruit Grafting workshop in Goffstown on Wednesday but you can contact Mary West at 796-2151 to see if there is room for you. There are pruning demonstration workshops coming up soon. Blueberries and raspberries this Saturday afternoon at Pratt Berry Farm in Lancaster NH. Ornamental trees and shrubs this Saturday at UNH’s Woodman farm in Durham. Looking well ahead on the calendar there will be another tree fruit twilight meeting on May 15th at Patch Orchard in Lebanon, with opportunity to earn some pesticide applicator credits.

April 18, 2019

Reports of green tip have been coming in from southern regions of the state. With rainshowers predicted in this weekend’s forecast, those apple growers with green tissue showing may want to apply a protectant fungicide due to high risk of apple scab infection.

April 15, 2019

Growing degree day accumulation for Durham 68, Hollis 82. We’re seeing swelling buds but no green tissue yet. 

Risk models for primary infection period for apple scab begin when 50% of macs are at green tip so that’s when we start looking at risk for infection events.

It’s pretty muddy out there but you should be thinking about getting in an application of dormant oil between green tip through tight cluster for smothering overwintered mite eggs and overwintered San Jose scale. Large spray volumes are recommended for getting really good coverage and the standard rate is 2 gallons per 100 gallons of water until half-inch green or 1 gallon per 100 gallons of water at tight cluster. The lower concentration lowers risk for phytotoxicity as more new growth emerges. Applying dormant oils with 48 h of freezing temperatures should also be avoided, or you could use a lower concentration, and it looks like that won’t be an issue in the upcoming weeks, but you never know these days, so keep an eye on your forecast.

There is a Tree Fruit twilight meeting at Butternut Farm on Wednesday April 17 from 5:30-7:30 pm, 195 Meaderborough Road, Farmington, NH. That will come with 2 pesticide credits.

Other opportunities for earning pesticides credits, and for brushing up on your pruning techniques: There are pruning demos and grafting workshops coming up with Saturday April 20 in Tuftonboro and next Tuesday April 23 in Hillsboro. Check out for more information.

April 8, 2019

Still not too much to report. Degree days accumulation as of today is 40 at Durham, 49 at Hollis.

The wet weather this week will make getting into the orchard a challenge but you may still have time to apply a dormant fungicide in peaches that were affected by peach leaf curl last year if you did not spray for it before leafdrop last fall.

For blueberry growers with a history of mummy berry, it might be a good time to rake mulch in blueberry plantings. A 2” layer of new mulch is enough to burry the mummies on the ground. Those mummies sources of fungus spores and new infections this year.

There will be a twilight meeting for commercial tree fruit growers next Wednesday the 17th at Butternut Farm in Farmington at 5 pm. For more information, visit

April 1, 2019

Not much to report yet, we’ve accumulated roughly 33 degree days here in Durham, 35 in Hollis.

But this is a good time to consider delayed-dormant sprays of petroleum/dormant oil (green tip through tight cluster). Large spray volumes help with good coverage, which is particularly important for smothering overwintered mite eggs and the nymphs, or “crawlers”, of San Jose scale and Comstock mealybug, which start moving around this time of year.

UNH pesticide safety training will be offered in Dover for prospective private and commercial applicators starting next week. Find more information at our website:


Anna Boudreau Supports Extension

I Support Extension

Anna Boudreau
State Advisory Council Chair, Natural Resources Steward and NH Coverts Cooperator