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Curiosity and expertise earn Excellence in IPM award for Cornell ‘pumpkin whisperer’

'Pumpkin whisperer' checks in with her 1,872-pound patient.

‘Pumpkin whisperer’ checks in with her 1,872-pound patient.

NYSIPM program news release:

Meg McGrath, a Cornell University plant pathologist based at the Long Island Horticultural Research and Extension Center, is an internationally recognized researcher, sought-after speaker, and well-versed in the solutions to devastating plant diseases.

And for growers with trouble on their hands, she’s available at a moment’s notice.

These qualities and more have earned McGrath an Excellence in IPM award from Cornell University’s New York State Integrated Pest Management Program (NYS IPM).

McGrath’s expertise spans the gamut of IPM strategies and tactics that both organic and conventional growers use to combat disease pests such as late blight and downy mildew. “Meg embraced the concepts of integrated pest management from the beginning of her career,” says colleague Margery Daughtrey. “She does a splendid job of bringing her discoveries to the practical level for growers in dozens of presentations annually.”

But it’s her help in the field that farmers value the most — help that’s delivered with a welcome dose of levity. “Meg’s funny,” says Marilee Foster at Foster’s Farm in Sagponack. “She’ll say ‘I’m sorry, I’m a plant pathologist. I like to study sick plants.’” When a nearby outbreak of late blight threatened Foster’s organic heirloom tomatoes, Meg came to help scout — “arriving early so we’d have the visual benefit of dew,” Foster says.

When they found a handful of plants with symptoms, McGrath reviewed Foster’s alternatives, but none were suited for organic crops. The strategy they hit on together? Using a handheld weed-flamer to take down suspect plants. “Blight can’t handle temperatures much above eighty degrees,” Meg told Foster. “And it might feel good!”  Which, Foster agrees, it did.

Meg focuses on core IPM principles — principles such as careful identification so you don’t treat a disease the wrong way, or changing a crop’s environment to outsmart its pathogens. “She helps Long Island growers deal with the limited availability of products they can use to manage pests, given the island’s heightened groundwater concerns,” says Jennifer Grant, director, NYS IPM. “It’s not every day you find someone who brings such warmth and knowledge to a position that means so much to so many farmers’ livelihood.”

Marilee Foster echoes that. “I have long admired the energy and curiosity Meg brings to farmers in eastern Long Island. We are lucky to have her working with us, for everyone.”

McGrath received her award on January 18 at the 2017 Empire State Producers Expo in Syracuse, New York. Learn more about integrated pest management at

More information:

New photo gallery: Phytophthora blight on eggplant

Symptoms of Phytophthora blight on eggplant include leaf spots that can be large, fruit rot, crown rot, and dieback of the growing tip.  Plants with the last two symptoms often die.

This disease has been more commonly found in cucurbit crops (especially pumpkin and squashes) and peppers.  Other susceptible crops are tomato and snap bean.

Read more.


New photo gallery: Bloat nematode of garlic

Bloat (aka stem and bulb) nematode was confirmed on garlic four times on Long Island between 2010 and 2016.  This nematode (Ditylenchus dipsaci) occurs where contaminated cloves were planted.  It can survive in soil for at least 4 years.  Dry soil favors survival.

Above ground symptom is yellowing of foliage and plant stunting, which has been noticed in late spring.  Twisting of foliage can also occur.  These symptoms are due to the nematode feeding on roots.  All roots may be gone.  Rot often doesn’t extend far into the bulb unless other organisms, in particular soft rot bacteria, are present.

Read more.


New photo gallery: White mold on tomatoes

White mold (aka timber rot) has been observed occasionally on Long Island in tomatoes growing in the field and in high tunnels.  Other crops observed affected in the area include pepper, lettuce, and cabbage.

Diagnostic feature for white mold is the black, hard structures resembling rat droppings the pathogen forms on or in diseased tissue (sclerotia).  These are inside tomato stems that are white and dry because of the disease.  Sclerotia are how the pathogen survives for many years.  It is worthwhile, especially in high tunnels, to remove affected plant tissue and thus the pathogen’s survival structures.

Read more.


New Photo Gallery: Phytophthora blight on beans

Beans are not as commonly affected by Phytophthora blight as other crops, notably cucurbit crops and peppers.  Beans have not been recognized as a host for the pathogen (Phytophthora capsici) for very long.  First report was 2003 in Michigan.  In 2008 the disease was confirmed on Long Island, and subsequently was observed in upstate New York.  Symptoms can be limited to pod rot.  Varieties producing long pods touching the soil are most likely to be affected.  Blight affecting whole plants has been observed in low areas of fields following rainstorms that resulted in standing water.


Read more.

New photo gallery: Sunscald of Pumpkin and Winter Squash

Sunscald damage to fruit can occur when exposed to sunlight as a result of loss of leaves.  The potential for this to happen increases substantially in the fall because leaves have died and heavy dews common in the fall can exacerbate the problem. Pumpkin and winter squash fruit are especially prone to sunscald.  Affected fruit are seen every year on Long Island in fall.

Read more and view photos.


New photo gallery: Septoria leaf spot of Parsley

Symptoms are small brown leaf spots, sometimes with characteristic tan centers and tiny black round structures (pycnidia) where the pathogen’s spores are produced.  Tiny, dark brown spots (usually less than ¼ inch in diameter) also develop with bacterial leaf spot, therefore it is important to look for the diagnostic pycnidia in the spots to distinguish these diseases.

Read full description and view more images.

septoria on parsley

New photo gallery: Anthracnose in cucurbit crops

Anthracnose occurs occasionally in cucurbit crops in the Northeast.  Following pictures of cucumber leaves taken on 7 and 15 August in 2014 show how symptoms can change in appearance in just one week.  The circular leaf spots are initially water-soaked, then become yellow to tan.  Round, black, sunken spots can develop on fruit.  On fruit spots the pathogen produces diagnostic salmon-colored spores under moist conditions.


View photo gallery.

New photo gallery: Fusarium crown rot and fruit rot of pumpkin

fusarium-pumpkin5x640The fungus Fusarium infects crown, root, and fruit tissue of pumpkin.  Symptoms have been observed on Long Island in fields where there is limited rotation, such as those used for u-pick, suggesting that it takes time for pathogen population to increase to a damaging level.

It is important to distinguish Fusarium crown rot from Phytophthora blight because conventional fungicides with targeted activity against Phytophthora are not effective against Fusarium.  Plants wilting and dying from Fusarium crown rot are rotten at the crown area extending downward into the main root, internal tissue is yellow to orange while plant tissue infected by Phytophthora is collapsed, dark on the outside and inside, and occurs at the crown and further up on the vine with the roots often not affected.  Fusarium crown rot tends to affect plants scattered throughout a field while Phytophthora blight is more often in areas where soil water drainage is poor.  Both pathogens can survive in soil for years. 

Continue to photo gallery

Disease Alert: Spinach downy mildew

The ‘Late blight’ of Spinach Developing Now in Northeast. See It?  Report It!  Manage It!

Downy mildew has been found recently in spinach at several farms in the northeastern U.S.  This devastating disease has not been confirmed in the region for several years, thankfully as it has been a major production constraint in California.  Pathogens causing downy mildew are Oomycetes and thus are related to the late blight pathogen.  They are similar in ability to produce an abundance of wind-dispersed spores capable of moving long distances and to not need leaves to be wet to infect (high humidity is sufficient), plus ability to devastate crops. 

All growers with spinach should inspect their plants for symptoms promptly NOW and also in spring plantings to catch if there is carry over or new outbreaks.  If downy mildew is suspected, please contact your local extension specialist and send an e-mail to

It will be CRITICAL that all high tunnel and overwintering spinach crops with downy mildew be destroyed couple weeks before the start of the spring spinach production season in the region to avoid carry over into 2017.

Purplish-gray, fuzzy growth on the underside of leaves. Click for larger view.

Purplish-gray, fuzzy growth on the underside of leaves. Click for larger view.

Symptoms.  Purplish-gray, fuzzy growth of the pathogen, which is usually on the underside of leaves, is diagnostic.  Early morning is the best time to see as the growth (which is spores and the structures holding them) is produced overnight, then during the day the spores are dispersed.  On the top side of leaves, opposite where the growth develops, the leaf tissue will be yellow, initially dull becoming brighter and larger with time.  Subsequently affected tissue will become dry and tan.  If only leaf yellowing is seen, which could occur when humidity is low, put suspect leaves upside down on wet paper towel in a closed ziplock bag for a day.  Keep the bag in the dark, such as inside a box, to further promote the pathogen if present to develop.

Management.   Resistant varieties have been an important management practice, but the pathogen has proven adept at developing new races able to overcome host resistance.  Last year race 16 was discovered.

Yellowing leaf tissue on top side of leaves opposite the fuzzy growth underneath. Click for larger view.

Yellowing leaf tissue on top side of leaves opposite the fuzzy growth underneath. Click for larger view.

To maximize success of control with fungicides, start early in disease development (preventive best), and apply weekly.  Conventional fungicides for this disease include: Actigard, Aliette, Merivon, Quadris and other QoI fungicides, ProPhyt and other phosphorous acid fungicides, Ranman, Reason, Revus, Ridomil Gold, and Tanos.  Downy mildew is difficult to manage with organic fungicides based on experience of researchers and growers in CA.  Labeled products include copper, Actinovate, Double Nickel, Regalia, Oxidate, Trilogy, and Zonix.  Copper is considered most effective but based on few evaluations of organic products.  Check REI and PHI when selecting conventional or organic fungicides to make sure fits production schedule.

Note that while leaves are held in plastic bag after harvest, affected leaves may rot and new symptoms may develop, especially if there is residual moisture from washing.

Promptly destroy infected, abandoned crops to eliminate this source of inoculum for other plantings in the region.  The pathogen can survive a few years in soil when both mating types are present together enabling production of oospores.

Other Susceptible Plants.  The pathogen, Peronospora farinosa f. sp. spinaciae, is only known to infect spinach.  It is possible some Chenopodium weed species are susceptible to some races.

Pathogen Sources.  It is possible contaminated seed or infected spinach produce from outside the region was the source of the current outbreak.

Favorable Conditions.  Cool with high humidity.  Optimal temperature range for this pathogen is 59 – 70 F.

Margaret Tuttle McGrath
Plant Pathology and Plant-Microbe Biology Section, SIPS, Cornell University
Long Island Horticultural Research and Extension Center
3059 Sound Avenue, Riverhead, NY 11901;

Please Note: Any reference to commercial products, trade or brand names is for information only; no endorsement is intended.  The specific directions on fungicide labels must be adhered to — they supersede these recommendations, if there is a conflict.  Check state registrations and labels for use restrictions.

Prepared 11/14/16

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