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

June 11, 2019

DD accumulation since 1Jan in Durham is (base 43) = 684, (base50) = 316.

We’ve been enjoying some lovely weather but it looks like rain is in the forecast this week. Scout for apple scab lesions and keep an eye on those apple scab models, with your risk levels in mind.

Plum curculio is likely laying its eggs in apple orchards now, so continue to scout for fresh oviposition scars to determine whether or not to treat. I heard some reports of first capture of codling moth adults last week, so right on time according to degree day estimates. Ovicides for codling moth should go out now.  Treatments for codling moth larvae should be timed for egg hatch, which occurs about 220 DD (base50) after first trap catch.

Reports of SWD first trap capture continue to roll in from areas south of us here in New Hampshire so, if you are monitoring for SWD in crops like strawberry, blueberry, and summer raspberry, you should get those traps out soon.

For those of you with serious winter injury to your blueberries, FSA is considering a disaster relief program so reach out to me or to your county specialist if you think this would be helpful to you.

Grapes: Peak flight of the overwintering generation of grape berry moth normally occurs at 350-400 GDD, this also often coincides with wild grape bloom. So keep an eye out for that if you know you have a

There is a tree fruit twilight meeting scheduled for this Wednesday, June 12th at Meadow Ledge Farm, 612 NH-129 Loudon, 5:30-7:30. Pesticide applicator credits will be available. Special Topics:  BMSB Trapping, Apple Processing, USDA Wildlife Service.

June 3, 2019

DD accumulation since 1Jan in Durham is (Base43)= 536, (Base50) = 224. Many apples are at post petal fall. Fruitlets are sizing up quickly and are susceptible to plum curculio so now is a good time to get out and scout for oviposition scars. According to the models, apple scab primary infection period is over in most areas. Now might also be a good time to scout for apple scab lesions on leaves and on fruits. Walk a transect through the orchard and examine the leaves and fruits of at least 10 clusters on at least 10 trees.

First capture of codling moth, or CM “biofix” normally occurs around now 200-300 GDD (base 50), but timing codling moth treatment is best when you have first catch data for your own farm. If you are using an insecticide that needs to be present before egg laying, it should be applied about 50-75 DD after first capture and if you are targeting young larvae, eggs normally hatch after about 220 DD after first capture.  

The same goes for San Jose scale, where treatment for crawlers should be timed at roughly 310 GDD after first capture of flying males. That first flight should be happening soon between 300-400 GDD from Jan1, but trapping is the best way to know what’s going on at your farm.

Reports of SWD first trap capture are rolling in from areas south of us here in New Hampshire so, if you are monitoring for SWD in crops like strawberry, blueberry, and summer raspberry, you should get those traps out soon.

For strawberry, keep scouting for tarnished plant bug during bloom. Threshold is reached if 4 or more flower clusters are infested with nymphs out of 30 clusters sampled evenly from across the field…and keep an eye out for thrips as these guys might come out while you’re tapping those flower clusters. Look for spider mites on the undersides of leaves and keep a record of hot spots that might need attention later as conditions warm up and dry up. The action threshold is when 25% (i.e., 15 leaves) or more of a 60 leaf sample is infested.

It sounds like orange rust of brambles could be a problem with the wet spring we’ve had so if you come across this you should cull out affected plants.

Events in the near future: there is a tree fruit twilight meeting scheduled for next week, June 12th at Meadow Ledge Farm in Loudon, 5:30-7:30. Special Topic:  BMSB Trapping, Apple Processing, USDA Wildlife Service. Pesticide applicator credits will be available.

May 28, 2019

We’ve been enjoying some beautiful weather here in the Durham area. DD accumulation (Base43)= 468, (Base50) = 195. Many apple varieties and blueberry varieties are still blooming.

According to the NEWA model apple scab ascospore maturity is at 99% so primary infection period is wrapping up, but there is rain in the forecast for many areas of the state so not quite out of the woods yet for potential infection periods.

Hopefully you’ve been checking your fireblight risk models regularly while your apple trees are blooming, especially if you had fireblight in your neighborhood last year. It’s supposed to rain in Durham this afternoon so today’s risk for fireblight infection is extremely high here. If I had trees in bloom here, I would want to get an antibiotic on today or tomorrow.

Planning for petal fall, this period is the best time to consider controls for plum curculio, European apple sawfly, obliquebanded leafroller, codling moth, European red mite. Plum curculio is likely already active in your orchard but females will start laying eggs in fruit once they get to be about a quarter of an inch in diameter. Look for fresh oviposition scars to trigger a control measure and consult your guide for selecting crop protection materials. Continue to scout for those fresh scars over the following weeks and consider a border spray for subsequent controls as this is normally sufficient.

For peaches, lesser peach tree borer starts flying around 476-668 (base 43), 250-370 (base 50). So if you are monitoring for borers, your traps should be up by now.

Once strawberry starts blooming, scout for tarnished plant bug by shaking flower trusses over a flat white surface. Alan Eaton always had a white Frisbee to do this but a white piece of paper will do. Tarnished plant bug nymphs are small and bright green. They kind of look like an aphid but they’re a lot more active, meaning they’ll run off that white paper pretty quickly. Threshold is reached if 4 or more flower clusters are infested with nymphs out of 30 clusters sampled evenly from across the field.

As far as events: we have another Tree Fruit Twilight meeting scheduled for June 12 at Meadowledge Farm in Loudon. If you missed our last meeting at Patch Orchard in Lebanon, so did I. George, Jeremy, Heather and I recorded a quick conversation where they caught me up on what we missed. I’m sending out an email with the link to this recording via the NH Vegetable & Fruit newsletter list so look for it later this week. If you’re not signed up for the newsletter, you can find directions for this on the extension website. Let us know if you’d like us to do more stuff like this.

May 21, 2019

We have many apple varieties blooming in the Durham area, as well as early varieties of blueberry. Peaches are still in bloom. Durham (Base43)= 343, (Base50) = 120.

For those who had fireblight in their neighborhood last year, check fireblight risk models on the NEWA website regularly while your apple trees are blooming. Our model for Durham says trees are at moderate to high risk and a bactericide should be considered.

Apple scab ascospore maturity is predicted to be at 91% in Durham so we are nearing the end of primary infection, but there is more rain in the forecast so continue to keep up with apple scab protection.

The same goes for brown rot and bacterial spot in peaches. Brown rot susceptibility starts to decline after shuck fall but considering all this rainy weather this will be a problem for many of you.

For those of you who monitor codling moth, you should have your traps up by now. First trap is anticipated around 200-300 DD(50) and that first capture establishes a biofix. This biofix is important for subsequent degree day accumulation that predicts peak CM flights on your farm through the year.

For many small fruit growers, we’ve been seeing and hearing about lots of winter kill in blueberry and raspberry. There’s a little discussion about whether or not to prune out dead wood in blueberry but you should probably hold off from pruning to wait and see if these dead canes are just delayed.  We’ll be providing more detailed guidance for this in a few weeks but for now, hold off on pruning and continue with your normal fertilization plans.

Mummy berry strikes may be showing up in blueberry soon. Consult the small fruit guide for more details on how to manage outbreaks.

Strawberry is also still wait and see as far as winterkill but this wet spring will produce perfect conditions for problems with Phytopthora infections. Red stele is caused by Phytopthora infections and symptoms are numerous and may be easy to confuse with winter injury: wilting; young leaves with a bluish-green tint; and older red, orange or yellow leaves. As plants progress and conditions dry up, severely diseased plants may die or remain stunted, producing few runners and small berries. Plants showing symptoms usually occur in patches where the soil was the wettest. When roots are cut open lengthwise, the core will show a reddish-brown discoloration; however, a reddish core does not guarantee that it’s red stele or Phytopthora – so send in samples to the diagnostic lab if you haven’t had this confirmed. If you know you have a history of red stele, consult your guide for protection recommendations.

Events: there is nothing from the Veg & Fruit Team in the immediate future but there is a backyard chicken basics workshop tonight, 6 pm at the Nesmith library in Windham, NH, for anyone interested.

May 14, 2019

Here in Durham, apples are at pink and peaches are in bloom. Durham (Base43)=250, (Base50) = 72

Apple Scab: For Boscawen: 61% mature ascospores (southern areas will be ahead, northern areas behind). Although many of the mature ascospores have been discharged, a scab infection period is predicted for the 14th. So, if you did not have a fungicide on prior to the infection, consider a kickback fungicide, especially if you had scab in the orchard last year.

Telial horns on cedar apple rust galls are still active.

Fire blight: With the southern portions of NH reporting some blossoms open on Macs (and earlier varieties), it’s time to monitor NEWA for fire blight. Go to newa.cornell.edu and click on apple diseases under the pest forecast tab. Select fire blight, NH, and the weather station closest to you. The date defaults to the current days date. When the model opens, select your orchard blight history, and enter the date of first blossom open. Hit the calculate button. The model will give you the current risk, and 5-day forecast.  The next few days will be too cold for infections, but keep monitoring the situation.

Pink stage is the last time to check for little green pug moth larvae and rosy apple aphid colonies – these can be yellow or powdery blue or pinkish. Act before bloom and before leaves surrounding blossoms curl up and around fruit clusters, thereby providing protection from sprays. Tarnished plant bug is likely moving into orchards soon and you might consider using white sticky traps to assess density. Redbanded leafrollers and spotted tentiform leafminers are flying. Peak flight for RBLR occurs at roughly 105-200 GDD (50), STLM at roughly 124-212. GDD (50).

For peaches: bloomtime is a good time to act for brown rot treatment, especially if you had brown rot problems last year…which is most of us. Consult the tree fruit management guide for product selection.

Raspberry and blackberry: we’ve seen a bit of winter damage on summer fruiting varieties and this may mean variable or delayed shoot growth along the cane.

For blueberry:  If you had problems with mummyberry last year, be sure to get 2” of mulch down ASAP (if you have not done so already).

There is a tree fruit twilight meeting this Wednesday on May 15th at Patch Orchard at 40 Patch Rd. in Lebanon, 5:30-7:30pm with an opportunity to earn pesticide applicator credits. For anyone interested in buying a hardcopy of the new Tree Fruit Management guide, you should be able to pick one up at this meeting or contact me at Anna.Wallingford@unh.edu or 603-862-1734. Hardcopies are $25 but the guide is always available online for free. For those of you that volunteer to monitor conservation easements in your area, extension is hosting a workshop this Saturday in New Durham – so check out the website for details.

May 7, 2019

Things are moving along nicely here in Durham. Apples are at tight cluster for the most part, however I’ve seen a little early pink, blueberries are at tight cluster, and peaches are in bloom.

In anticipation of apple bloom, if you had fireblight in your neighborhood last year, consider making sure you have a streptomycin product on hand. As we watch for risk indicators of blossom blight infections to come, it is best to be prepared.

Apple scab ascospore maturity is estimated to be 38% and the recent wet weather has provided prime conditions for infection events. You may want to take advantage of this nice weather and get a protectant fungicide on before the rain predicted for Thursday and Friday or make sure to have materials with some kickback on hand.

Cornell has just launched a new tool on their NEWA website to help with timing your thinning efforts. This tool can be found under the crop management drop down menu – its called “Apple CHO v2019” -and differs from the old model in a few ways. You can enter information about the flowering status of your crop to improve the precision of this decision making tool. Check it out at NEWA.cornell.edu.

For peach, bloom time is a good time to apply a fungicide for brown rot, especially if you had brown rot issues last year and did not take extensive sanitation measures over the dormant period. Tart cherries are also particularly susceptible to brown rot. Consult the tree fruit management guide for more information on selecting a product.

If you are using mating disruption for peach tree and lesser peach tree borers and haven’t put your ties out, they should go out soon.

Speaking of mating disruption and bouncing back to apple for a moment – we have news that NH registration was approved on CIDETRAK mating disruption products for codling moth and oriental fruit moth CMDA+OFM MESO, OFM-L MESO and DA MEC. So ask your supplier about that if you are interested but ask soon if you want to act this year because mating disruption has to go out before moths start flying.

In strawberry fields where Strawberry Bud Weevil/Clipper were a problem last year, now might be a good time scout fields as flower trusses emerge and expand for sign of this pest.  In the pre-bloom to early bloom period female clippers lay an egg in an unopened flower bud and then clip the stem of the bud causing it to flop over or fall off, obviously causing the loss of that fruit. Clipper tends to be a more severe problem along borders of plantings, near woods, hedgerows or stonewalls. Treat for clipper when you find an average of more than 3 highly damaged flower trusses per meter of row. You might consider only treating border rows, especially rows bordering woods, hedgerows and stonewalls. Do not treat during bloom.

For brambles - As leaf tissue expands, watch for orange rust on blackberries and black raspberries and rogue out plants where it is found.  Orange rust is systemic and cannot be treated to eliminate it from an infected plant.

Next week there will be a tree fruit twilight meeting on May 15th at Patch Orchard at 40 Patch Rd. in Lebanon, 5:30-7:30pm with an opportunity to earn pesticide applicator credits.

April 30, 2019

There has been quite a bit of variability in fruit tree development depending on where you are in the state and the microclimate on your farm. GDD (base 43): Durham – 172 (last year 105), Hollis – 216 (last year 124)

Our plant pathologist, Cheryl Smith has reported that Jellie horns are out on cedar apple rusts so trees are at risk of infection with rains. In Durham, we estimate 11% apple scab ascospore maturation. This, as well as lots of rain, puts apple orchards at high risk of apple scab infection. Consult your management guide for crop protection materials.

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. Presence of these sporadic pest species may trigger an insecticide treatment before bloom. Insecticide sprays during bloom are discouraged in order to avoid negative impacts on pollinators in the orchard. However, there are selective insecticides (like Dipel) which have efficacy on caterpillars like winter moth and pug moth but little effect on pollinators.

For blueberry – wet weather means continued risk for mummy berry infection. Cleaning up fallen mummies, or covering them with at least 2” of mulch is a helpful sanitation practice. Consult the guide for effective fungicides.  If your blueberry plants are affected by any species of scale insect, a dormant or delayed-dormant oil spray may still be appropriate. If you do have green tissue, make sure the oil product you are using specifically allows for delayed dormant applications.

For strawberry – As foliage expands, now is a good time to start tracking weak areas of the field and check roots for Black Root Rot or signs of Red Steele if you find stunted or sparse growth. Check the extension websites for details on how to submit plant samples to the diagnostic center if you think you have a disease problem, but best management practices call for proper nutrition and proper timing of renovation to allow for good winter preparation in the fall.

Events - It sounds like registration is full for the Women’s Farm Equipment Field day on May 4th but you can contact elaina.enzien@unh.edu or (603) 679-5616 to see if there’s room for you, or to encourage more events like this in the future. 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 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 extension.unh.edu 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 extension.unh.edu

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: extension.unh.edu.

 

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