Andy Wyenandt

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

April 24, 2018

Damping-off: Identifying and Controlling Early-Season Pathogens

It is extremely important to know which pathogen is causing damping-off problems and which fungicide to properly apply. The key to controlling damping-off is being proactive instead of reactive. Always refer to the fungicide label for crop use, pathogens controlled, and application rates.

Damping-off is caused by a number of important vegetable pathogens and is very common during the spring. Damping-off can kill seedlings before they break the soil line (pre-emergent damping-off) or kill seedlings soon after they emerge (post-emergent damping-off). Common pathogens that cause damping-off include Pythium, Phytophthora, Rhizoctonia and Fusarium spp.

Control of damping-off depends on a number of factors. First, is recognizing the conditions which may be leading to the problem (i.e., weather/greenhouse growing conditions) and second, identifying the pathogen causing the problem.

Conditions Favoring Damping-off

Although all four pathogens are associated with damping-off, the conditions which favor their development are very different. In general, Phytophthora and Pythium are more likely to cause damping-off in cool, wet or overwatered soils that aren’t allowed to dry out due to cloudy weather or cooler temperatures. Conversely, Rhizoctonia and Fusarium are more likely to cause damping-off under warmer, drier conditions especially if plug trays are kept on the dry side to help reduce transplant growth. [Read more…]

Filed Under: Organic Production, Vegetable Crops
April 24, 2018

Controlling Spring Diseases in Asparagus

Asparagus season is just around the corner and now is a good time to review important diseases.

Wet soil conditions are ideal for Phytophthora and Pythium development. To help reduce potential losses, especially in fields with low spots or fields that are poorly drained soils, or more importantly, in fields with a history of either disease apply Ridomil Gold 4SL (mefenoxam, 4) at 1.0 pt/A, or Ultra Flourish 2E/A (mefenoxam, 4) at 2.0 pt/A, or MetaStar 2E (metalaxyl, 4) at 2.0 qt/A over beds just before first harvest. For new plantings, apply the same after planting or after crown covering. Do not apply Ridomil or MetaStar one day prior to harvest or illegal residues may result. [Read more…]

Filed Under: Vegetable Crops Tagged With:
April 24, 2018

Controlling Strawberry Fruit Rots – 2018

Anthracnose fruit rot of strawberry

Anthracnose Fruit Rot of Strawberry

Fruit rots in strawberry can cause significant losses if not recognized early and controlled. The use of good cultural practices such as keeping fields weed-free and promoting good drainage, long crop rotations, and preventative fungicide applications are critical.

Pathogens such as anthracnose, gray mold (Botrytis), and leather rot (Phytophthora) can become systemic problems in strawberry plantings once established. All three fungal diseases are soil-borne and once in fields can be difficult to manage over the lifetime of the planting.

The use of mulch (matted rows) to prevent/reduce soil splashing and keeping fruit from coming into direct contact with the soil surface can be beneficial in organic production systems where conventional fungicides cannot be used. Use of long crop rotations and staying away from areas of the farm with known instances of any of these pathogens is also important. Remember that same species of Colletotrichum that causes fruit rot in pepper and other crops can also infect strawberry.

[Read more…]

Filed Under: Vegetable Crops Tagged With: , ,
February 20, 2018

Fungicide resistance management guidelines for cucurbit powdery and downy mildew control in 2018

Extension specialists in the mid-Atlantic and Northeast regions have put together new guidelines for cucurbit powdery and downy mildew control. These new guidelines list all recommended fungicides and their efficacy ratings for controlling both diseases based on recent fungicide efficacy trials. Also included in the new FRAC table are notes on fungicides where resistance has been detected in the region. The new FRAC table can be  downloaded for FREE on American Phytopathology Society’s Plant Health Progress website.

Filed Under: Vegetable Crops Tagged With: , ,
January 12, 2018

Best management practices for managing Dickeya dianthicola in potato.

Its the time of year when many potato growers (organic and conventional) are preparing to purchase seed potatoes for the upcoming season. Dickeya dianthicola was detected in ‘Dark Red Norland’ and ‘Kennebec’ seed being sold in retail establishments and in ‘Silverton’ in a commercial seed lot in NJ in 2017. Importantly, all growers are encouraged to follow best management practices for buying seed and best management practices for Dickeya in field production. North American Seed Health Certification records and Dickeya test results should be requested prior to purchasing any seed.  If you suspect Dickeya dianthicola in potato seed during purchasing, cutting, or planting please contact your county Extension agent or Extension Specialist. All suspect potato samples should be PCR tested to confirm the presence of Dickeya or Pectobacterium.

This past fall The University of Maine held a Dickeya and Pectobacterium Summit which was attended by over 150 people from all over the world. A nice summary of the meeting by Dr. Angela Madeiras can be found in the January 11, 2018 UMASS Vegetable Notes Newsletter here.

 The best method for keeping your potato operation Dickeya-free is to adopt your own 0% Dickeya-tolerance policy.

Filed Under: Vegetable Crops Tagged With:
September 24, 2017

Vegetable Disease Update – 9/24/17

  • Late blight has been reported in western NY and Long Island this past week. Late blight has not been reported on tomato or potato in NJ to date. If you suspect Late blight on your farm please contact your county Extension agent. To track the progress of Late blight in the US please visit USAblight.
  • Cucurbit downy mildew (CDM) continues to be reported throughout the region. All cucurbit growers are encouraged to continue to include downy mildew specific fungicides in their regular weekly maintenance programs. To track CDM movement in the US please visit the North Carolina State University’s CDM Forecasting Website.
  • Fusarium and Rhizoctonia root rot has been reported in Cilantro and parsley this past week.
Filed Under: Vegetable Crops