Archives for August 2013

August 27, 2013

Tomato Disease Forecasting Report 8-27-13

8-27-13 Tomato Report – Click to Download

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
August 25, 2013

Wave That Flag

… summertime gonna come and go by and by. As the weather changes from the dog days of summer to a more “fall-like” pattern, I am feeling pretty good; but so is the fungus that causes dollar spot.

Dollar spot on bluegrass surround. Photo: Matt Roderick, Oakley Country Club

Dollar spot on bluegrass surround. Photo: Matt Roderick, Oakley Country Club

[Read more…]

Filed Under: Landscape, Nursery, & Turf, Plant Diagnostic Lab Tagged With:
August 23, 2013

Grape Injury
from Captan Mixed with Oil-containing Products

Fig 1 Captan induced Leaf Necrosis in Grape

Fig 1 Captan mixed with oil-containing product
induced leaf necrosis in grape

When used properly Captan is a safe and effective fungicide that plays an important role in grape disease control and fungicide resistance management, but it is crucially important to never apply Captan mixed with oil or close in time to the application of any oils. The active ingredient in Captan cannot easily penetrate into the plant, but when it does it can be very toxic, especially to grapes. Injury from this type of spray combination has been reported in blueberries and there are many anecdotal reports of less severe phytotoxicity in other fruit crops. By comparison, the damage to grapes can be very severe and the symptoms include leaf necrosis, longitudinal stem splitting and vine death (Fig. 1, 2, 3). Sadly, experience has shown that under the appropriate conditions a single spray of Captan with an emulsifiable concentrate insecticide can kill an entire vineyard. [Read more…]

Filed Under: Wine Grape
August 22, 2013

Pepper Weevil Resurgence

In the past two weeks there has been an increase in the number and locations of pepper weevils caught in traps.  From the end of June to the first part of August all of the weevils caught were in Woolwich Township on both non-farm and farm traps.

The locations where weevils have been caught or found since August 8 now include Woolwich Township, Logan Township, Cherry Hill Township, Vineland, East Vineland, and Cedarville.  No weevils have been caught recently in the Hammonton area.  This pattern of spread is similar to 2012 when there were no trap captures of weevils in June and July, but suddenly in mid-August seemed to be everywhere.

Infested fields now range from garden-sized pepper plots to full-size commercial fields.  The spike in numbers caught at one field, this year, coincides with the arrival of off-farm produce bins.  Given the locations of non-farm traps, it’s apparent that we do have multiple introductions of pepper weevil through the growing season.

Concerns about pepper weevil have been negated by too much rainfall and resulting disease problems this year.  However, if no preventive action is taken in newly infested fields there will be economic loss even at this time of year.  Farmers must figure out the cost of control versus the revenue likely from late season peppers.  Although several insecticides will kill adults, weekly rotations of Actara and Vydate seems to perform the best.

For specific numbers and locations where weevils have been caught in the past two weeks, refer to this week’s Vegetable IPM Update.

Filed Under: Vegetable Crops
August 22, 2013

Potato Disease Forecasting Report 8-22-13

Potato Disease Forecasting Report 8-22-13 – Click to Download

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.

Filed Under: Disease Forecasting
August 22, 2013

Tomato Disease Forecasting Report 8-22-13

8-22-13 Tomato Report – Click to Download

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