Andy Wyenandt

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

October 13, 2014

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.

20141003_102835

Photo 1: Internal Fruit Rot

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Photo 2: Growth Cracks

Filed Under: Vegetable Crops Tagged With: ,
October 3, 2014

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: ,
October 1, 2014

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

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.

Filed Under: Vegetable Crops
October 1, 2014

Cold Injury in Cucumber

The effects of a cold night a few weeks ago are showing up in some varieties of cucumber around New Jersey. Symptoms on maturing fruit appear as brownish-tan areas on the epidermis of fruit. The fruit will also show cracking as if it has a dry rot. The effects are physiological where areas of young developing fruit got chilled by the cold night time temperatures.

Cuke_cold injury

Cold injury on cucumber fruit. The initial damage was done a few weeks ago while the fruit was very young.

Filed Under: Vegetable Crops Tagged With: ,
September 29, 2014

Managing Cercospora in Beet

Cercospora leaf spot can significant losses in beet if not controlled properly.

Cercospora on beet.

Cercospora leaf spot on beet. Note the round tan leaf spots with dark red margins.

The fungus overwinters in soils and be a continual problem in fields with short crop rotations. It has developed resistance to important fungicides in beet production areas in the US and abroad. Resistance has been detected in the Benzimidazole fungicides (FRCA code 1); the DMI fungicides (Tilt, tebuconazole; FRAC code 3) and the strobilurin fungicides (Quadris, Cabrio, Headline; FRAC code 11). Beet growers in NJ who have relied heavily on, and are not obtaining adequate control of Cercospora with either DMI or strobilurin fungicide applications in their weekly programs should discontinue their use. These growers should switch to fungicides with different modes of action such as Fontelis (penthiopyrad, 7) at 16.0 to 30.0 fl oz/A (3 day PHI) and Merivon (fluxapyroxad + pyraclostrobin, 7 + 11) at 5.5 fl oz/A (7 day PHI). Growers who are still obtaining adequate control with either the DMI or strobilurin fungicides can continue their use, but should make efforts to incorporate the use of the mentioned fungicides above to help reduce the chances for resistance development.

Merivon Supplemental Label

Filed Under: Vegetable Crops Tagged With: ,