Andy Wyenandt

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

July 12, 2015 Andy Wyenandt

Intro to Organic Vegetable Production Field Day from Penn State, Aug 6, 2015

Location
Good Work Farm
4791 Rock Road
Zionsville, PA 18092

Date: August 6, 2015 from 4 to 7 pm
4:00 PM Farm Tour
4:45 PM Scouting and Identification Exercise
5:45 PM Disease Management and Discussion
6:30 PM Dinner

Registration
This field day is part of the Introduction to Organic Vegetable Production series. No pre-registration is required. Walk-in to join us. $10 walk-in fee covers dinner and materials.

Penn State Extension is offering An Introduction to Organic Vegetable Production Field Day focusing on plant disease scouting, identification, and management on the evening of August 6th at Good Work Farm in Zionsville, PA located about an hour north of Philadelphia. For more information see Organic Vegetable Production Field Day.

Filed Under: Organic Production, Vegetable Crops

July 12, 2015 Andy Wyenandt

Of Note from UDel: Late blight Look-a-like in Potato & Late blight Lineages

Two important topics were addressed by Dr. Nathan Kleczewski, Extension Specialist in Plant Pathology at the University of Delaware this week in the Weekly Crop Update.

We have on occasion detected Phytophthora nicotiana on potato in southern New Jersey when wet weather conditions have been prolonged. The good news is that P. nicotiana, although it looks like Late blight, does not show anywhere near the destructiveness that comes with Late blight.

Last week Late blight, Phytophthora infestans, (US23) was found in tomato in Northern New Jersey. US23 has been the predominant genotype found throughout the region during the past few years. Why is knowing the genotype so important? US23 will infect both tomato and potato and has been shown be sensitive or to have intermediate-sensitivity to mefenoxam (i.e., Ridomil Gold). Knowing that US23 is present in New Jersey should put all tomato and potato growers on high alert and everyone should be scouting on a regular basis. All tomato and potato growers should initiate standard protectant fungicide programs if they already haven’t done so.

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

July 10, 2015 Andy Wyenandt

Verticillium Wilt in Eggplant

Verticillium wilt is a common soil-borne fungal pathogen that once it has infested soil can remain for a very long time. Verticillium wilt is caused by either Verticillium albo-atrium or Verticillium dahlia and has a wide host range (over 200 plant species). Both pathogens can survive (overwinter) as microsclerotia in the soil. Verticillium wilt prefers cooler weather and drier soils and can be more severe in neutral to alkaline soils. Solanaceous weeds such as Nightshade may harbor the pathogen.

Diagnostic symptoms of Verticillium wilt in eggplant
Photo by Kris Holmstrom

[Read more…]

Filed Under: Vegetable Crops Tagged With: eggplant, verticillium wilt

July 10, 2015 Andy Wyenandt

Leaf Mold in Tomato

Leaf mold (formerly Fulvia fulva) has been confirmed in field-grown tomatoes in Cape May County.

Leaf mold occasionally appears in high tunnel or greenhouse tomato production in New Jersey. However, under ideal conditions the disease will develop in field-grown crops. The fungus will cause infection under prolonged periods leaf wetness and when relative humidity remains above 85%. If relative humidity is below 85% the disease will not occur. The pathogen can survive (overwinter) as a saprophyte on crop debris or as sclerotia in the soil. Conidia (spores) of the fungus can also survive up to one year in the soil.

Symptoms of leaf mold on infected tomato plant. Note the bright yellow leaves and the olive-green spores developing on the undersides of leaves.

Symptoms of leaf mold on infected tomato plant. Note bright yellow leaves and olive-green spores developing on undersides of leaves.

[Read more…]

Filed Under: Organic Production, Vegetable Crops Tagged With: leaf mold, tomato

July 9, 2015 Andy Wyenandt

Cucurbit Downy Mildew Confirmed on Cucumber in NJ – ALERT – 7/9/15

Cucurbit downy mildew has been confirmed on cucumber in Salem County, New Jersey. This is the first report of cucurbit downy mildew in the state this growing season. The pathogen has also been found on watermelon in DE and MD and on cucumber in PA.

All cucurbit growers should consider adding a downy mildew specific fungicide to their weekly fungicide program. For more information on the control please see the 2015 Commercial Fungicide Recommendations Guide.

Filed Under: Vegetable Crops

July 9, 2015 Andy Wyenandt

Anthracnose and Alternaria Leaf Blight in Cucurbit Crops

Anthracnose and Alternaria leaf blights are showing up in cucurbit crops. Weather conditions in the region continue to be ideal for disease development across all vegetable crops. The regular rainfall and high humidity that have plagued the region only acts to exacerbate problems. All cucurbit growers should be on high alert for foliar diseases such as anthracnose and Alternaria as well as downy mildew. Anthracnose and Alternaria produce distinct circular spots on infected leaves, and in most cases, symptoms begin on the older leaves.

Symptoms of anthracnose on infected cucumber leaf.

With Alternaria, diagnostic concentric black rings will be develop within the spots. With Anthracnose, black setae (hair-like projections) will develop on the veins of infected tissue on the underside of leaves.

Anthracnose and Alternaria are easily controlled with weekly protectant fungicides such as chlorothalonil and mancozeb as long as they are applied prior to the arrival of the pathogen. Control of downy mildew will require downy mildew specific fungicides. As long as these weather conditions persist all growers need to remain on strict weekly protectant fungicide programs and be scouting on a daily basis. Organic growers can apply copper and other labeled products to help suppress development of these diseases.

Complete foliar coverage is critically important for the control these diseases.

For more information on the control of anthracnose and Alternaria leaf blight in cucurbit crops please see the 2015 Commercial Vegetable Production Guide.