Andy Wyenandt

This is an archive of Dr. Wyenandt's posts on the Plant and Pest Advisory.

January 20, 2015 Andy Wyenandt

2015 Fungicide Resistance Management Guidelines Available

The 2015 Fungicide Resistance Management Guidelines for Vegetable Crops is now available. This free publication, targeted to New Jersey and the surrounding mid-Atlantic region, helps vegetable growers understand and manage potential fungicide resistance development on their farm.

Click Image to View | Download PDF (1.9 MB)

In order to understand and use fungicide resistance management strategies effectively, first learn how and why fungicide resistance may develop; a series of articles is available on this website.

Filed Under: Vegetable Crops Tagged With: fungicide resistance management

October 13, 2014 Andy Wyenandt

Late Blight Still Active on Tomato

Late blight was confirmed in a homeowner garden today near Clementon, NJ (Camden County) and here at the Rutgers research station near Bridgeton, NJ (Cumberland County). This is a good reminder that as long as weather conditions are conducive, the threat of late blight in the state and region will continue until the first killing frost.

All abandoned tomato fields need to be destroyed either by mowing, discing under, or sprayed with a herbicide such as gramoxone to kill all living foliage. This is especially important if protectant fungicide programs have been discontinued. Homeowners can simply pull plants and put in their compost pile or discard in the trash.

Filed Under: Vegetable Crops Tagged With: Late blight, tomato

October 13, 2014 Andy Wyenandt

Internal Fruit Rot in Tomato

A fresh market tomato from a home owner garden was dropped off the other day with some strange internal rot. The internal rot (photo 1) was most likely caused by water accumulating in areas immediately around the stem and as the fruit developed growth cracks (photo 2). This allowed for opportunistic fungi and bacteria into infect the fruit causing the internal rot. As it turned out the home owner was using sprinklers to water their garden.

As the season continues into the late fall, it might be worthwhile to slice up one or more of your tomato varieties that are prone to growth cracks around the stem just to check if this is happening in your operation – especially with heavy dews and the wet weather we have had recently.

Photo 1: Internal Fruit Rot

Photo 2: Growth Cracks

Filed Under: Vegetable Crops Tagged With: internal fruit rot, tomato

October 3, 2014 Andy Wyenandt

Leaf blight in Dill

Leaf blight in Dill as shown up in the past week in some areas of southern New Jersey.

Leaflets on plants will appear wilted, often on the lower portion of the plant first. Up close, irregular lesions will appear scattered over the leaflets, girdling them, causing them to look wilted.

There have been a couple fungal pathogens associated with causing dill leaf blight. Options for controlling foliar pathogens in dill are extremely limited. Growers can apply Quadris (azoxystrobin, 11) at 15.5 fl. oz/A (O day PHI) alone or tank mixed with fixed copper on a 7 day schedule. Conventional growers can also apply a disinfestant, such as Oxidate, after overhead irrigation. Organic growers can apply OMRI-approved copper products. Other OMRI-approved products for leaf blight control may help suppress the pathogen.

Only overhead irrigate on sunny days in the in AM or early afternoon so planting can dry out.

Filed Under: Vegetable Crops Tagged With: Dill, leaf blight

October 1, 2014 Andy Wyenandt

Vegetable Disease Update – 10/1/14

Cole Crops
Pumpkin
Spinach

Cole Crops

Downy mildew and Alternaria – Symptoms of downy mildew include purple to yellowish-brown spots on upper leaf surfaces. A grayish-white spore mass will develop and cover the underside of leaves under ideal temperatures (night temperatures of 46 to 61°F and day temperatures below 75°F). Downy mildew can kill young plants. Heavily infected leaves may drop providing entry points for bacterial infections (i.e., black rot and soft rot).

Symptoms of Alternaria on infected leaves include small, expanding circular lesions with concentric rings that may have a ‘shot-hole’ appearance as lesions age. Heavily infected seedlings may result in damping-off.

Control of Downy mildew and Alternaria begin with preventative fungicide applications. Use one of the following at the first sign of disease and continue every 7 to 10 days (Please refer to the pesticide table on page F31 of the 2014 NJ Commercial Vegetable Production Recommendations to determine which fungicide is labeled for each specific crop.
[Read more…]

Filed Under: Vegetable Crops

October 1, 2014 Andy Wyenandt

Vegetable Disease Briefs – 10/1/14

Basil downy mildew remains active. The weather this time of year is ideal for downy mildew development across many crops. Growers should remain diligent going into the fall with regular scouting and preventative fungicide applications.

Cucurbit downy and powdery mildew remain active. Growers holding mature pumpkins in the field for the next few weeks should do their best to maintain the foliage for as long as possible to prevent potential sunscald injury. Late-season fungicide applications will also help keep powdery mildew off of the stems extending the pumpkin’s post-harvest longevity. Stems infected with powdery mildew will turn brown and dry out much quicker than healthier stems. Additionally, powdery mildew and downy mildew fungicide programs for all fall cucurbit crops should continue as along as harvesting continues.

There have been no new reports of Late blight this past week. Growers with late-season tomato plantings should be diligent and scout on a regular basis. The cooler weather and prolonged dew periods are ideal conditions for Late blight development. All old plantings should be sprayed with gramoxone to burn the foliage down or mowed/disced under as soon as possible after the last harvest.