Andy Wyenandt

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

May 5, 2014

Basil Downy Mildew Reported – NJ 5/5/14

Basil downy mildew was reported in a greenhouse in Virginia last week. The first question I asked myself was, “How can that be?”

BDM_OW_GH

Basil downy mildew on overwintered sweet basil plant.
Note symptoms on leaf top side and downy mildew spores on leaf underside.

Well, before I could come up with a good answer, basil downy mildew was found in a high tunnel in Salem County today. I don’t have any of the details from the VA report yet, but I do have a lot of information from New Jersey.

The infected plants in question, roughly 12 mature potted sweet basil plants, were just a few plants that were left over from last fall and carried over the winter in a non-heated high tunnel on benches with heated mats and row cover. The heated mats and row cover were for protecting other crops. Interestingly, the basil did not freeze out, somehow managed to survive the winter without much heat, and produce downy mildew spores once the outside temperatures rose.
[Read more…]

Filed Under: Vegetable Crops
May 1, 2014

Strawberry Fruit Rots

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 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:
April 23, 2014

Understanding Fungicide Resistance

Efforts have been made in recent years in New Jersey and the surrounding mid-Atlantic region to help vegetable growers understand and manage potential fungicide resistance development on their farm.

fungicide guidelinesSince 2007, Fungicide Resistance Management Guidelines have been available and distributed to vegetable growers throughout the region. Over, 20,000 FRAC guides have been distributed over the past 8 years at local, state, and regional vegetable meetings and conferences. Much of this work has been funded by the Northeast IPM Center.
The 2014 Fungicide Resistance Management Guide can be found on the right sidebar of the Vegetable Crops Online Resource Center and downloaded FREE. In order to understand and use fungicide resistance management strategies effectively one must first understand how and why fungicide resistance may develop. A series of articles is available on this website by clicking the links below.
Growers guide to understanding protectant fungicides (M1-M9)
Growers guide to understanding DMI fungicides (FRAC group 3)
Growers guide to understanding Strobilurin fungicides (FRAC group 11)

Filed Under: Vegetable Crops Tagged With:
April 23, 2014

Controlling White Mold

White mold, or lettuce drop, caused by Sclerotinia sclerotiorum, has been reported. White mold can cause serious losses in lettuce and other susceptible crops if left uncontrolled.

WhiteMold

White mold on lettuce. Notice the white fungal growth and black sclerotia developing on the base of the stem. The sclorotia can survive in the soil for up to 10 years.

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Filed Under: Vegetable Crops Tagged With:
April 14, 2014

Spear Damage in Asparagus

Spear damage in asparagus can be caused by diseases such as Phytophthora spear and crown rot and purple spot. However, other environmental factors during the spring can damage spears as they emerge from the soil.

Fig. 1. Wind damage of asparagus spears. Notice how all spears are pointed in the same direction

 Wind – Periods of heavy winds during emergence will cause spears to bend.

Winds can cause one side of the spear to dry out quicker than the other causing the spear to bend and point in the direction of the prevailing wind. An asparagus planting is suffering from wind damage if most of the bent spear heads in the bed are pointing in the same direction (Fig.1).

[Read more…]

Filed Under: Vegetable Crops Tagged With:
April 14, 2014

Controlling Spring Diseases in Asparagus

Asparagus season is just around the corner and now is a good time to review important diseases. With the long, wet spring we’ve encountered this year many fields have been extremely wet for long periods of time.

These types of 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 1st 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: