Archives for July 2015

July 10, 2015

Potato | Tomato Disease Forecast 7-10-15

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Potato Disease Forecasting Report

We will be tracking DSVs for Late blight development and calculating P-days for initiating the first early blight fungicide application.

The first late blight fungicide application is recommended once 18 DSVs accumulate from green row. Green row typically occurs around the first week in May in southern New Jersey. An early season application of a protectant fungicide such as mancozeb (Dithane, Manzate, Penncozeb) or Bravo (chlorothalonil) as soon the field is accessible is suggested. Please be vigilant and keep a look out for suspect late blight infections on young plants. No late blight has been reported in our region to date.

Remember the threshold for P-days is 300!  Once 300 P-days is reached for your location early blight fungicide applications should be initiated. Growers who are interested in using this model should chose the location above that is closest in proximity to their farming operation and should regularly check the Cornell NEWA website (http://newa.cornell.edu/) where this information is compiled from. Click on Pests Forecasts from the menu, select your weather station, and click on tomato diseases, set accumulation start date and a table of daily and total DSVs will be generated.

Tomato Disease Forecasting Report

Disease severity values (DSVs) for early blight, septoria leaf spot, and tomato anthracnose development are determined daily based on leaf wetness (due to rainfall, dew) and air temperature.

On a daily basis DSV values can range from 0 to 4 where 0 = no chance for disease development to 4 = high chance for disease development.
DSVs are accumulated during the production season.

Fungicide applications are based on an individually determined DSV threshold. The first fungicide application for the control of these three diseases is not warranted until 35 DSVs have accumulated from your transplanting date. After that, growers can base fungicide applications on different DSV thresholds.

Filed Under: Disease Forecasting
July 9, 2015

Fruit IPM Report 7-9-2015

Peach

Oriental Fruit Moth (OFM): While we are still between flights, trap counts indicate a slight pick up of moth activity for the start of the 3rd flight. The first insecticides will be due by the middle of the month in southern counties and about a week later in northern counties. Time your sprays according to the following table:
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Filed Under: Blueberry, Fruit, Tree Fruit
July 9, 2015

Veg IPM Update: Week Ending 7/8/15

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Sweet Corn

We are still between European corn borer (ECB) adult generations at this time. Very few individuals have been captured throughout NJ this past week (see ECB map). ECB infestations are almost gone from all sweet corn plantings. We would expect to see signs of the second flight within the next two weeks.

As always, consider treating when the number of infested plants in a 50 plant sample exceeds 12%. Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays.

See the 2015 Commercial Vegetable Recommendations Guide for insecticide choices.
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Filed Under: Vegetable Crops
July 9, 2015

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

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.

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.

Filed Under: Organic Production, Vegetable Crops
July 9, 2015

Want More Information on Late Blight, Cucurbit Downy Mildew & Other Vegetable Diseases?

Look for it in the Vegetable Crops Edition Sidebar (shown right).

As with Rutgers, other universities in the mid-Atlantic region share important information with vegetable growers in their respective states. Much of this information is extremely useful for conventional and organic vegetable growers in New Jersey. All of this information is shared, along with our own, through our Plant and Pest Advisory website! Important disease alerts and information is fed into our Plant and Pest Advisory from Delaware, Pennsylvania, and Virginia through the links that appear in the right side bar. All you need to do is click on the link!

Filed Under: Vegetable Crops