In February, I was scheduled to speak at a landscape program in Rockville, MD. Before I went on, I had a chance to chat with one of the other speakers–the esteemed entomologist from the University of Maryland, Dr. Mike Raupp–who said concerning the Emerald Ash Borer, “nobody believes you until the trees start dying.”
Archives for May 2016
Potato | Tomato Disease Forecast 5-13-16
Click to View | Download Report 5-13-16
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.
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.
Pest Alert: Probable Allium Leafminer infestations found in NJ
Two probable infestations of allium leafminer have been discovered. One of these was on the Hunterdon/Warren County border involving overwintered garlic and onions planted this spring. The second, a very minor infestation, was found near Princeton in Mercer County on overwintered chives. While we await word from USDA as to where specimens should be sent for final confirmation, the signs of infestation are very characteristic of allium leafminer, and larvae and eggs were found in association with the egg laying scars (oviposition scars) on the leaves of onions and garlic. Both of these infestations appear to be very recent, with larvae in very early growth stages. [Read more…]
New Fungicide for Peach Disease Control
The fungicide Luna Sensation has been registered for use on peach. This fungicide was previously registered on apple and cherry in 2012. Due to its recent release this spring for peach disease control, Luna Sensation was not included in the latest 2016 publication of the New Jersey Commercial Tree Fruit Production Guide. Thus, below is a discussion of its attributes and suggested usage for disease control on peach. [Read more…]
Vegetable Disease Briefs – 5/11/16
- Rhizoctonia root rot has been found on newly emerged cucurbit seedlings. The cool, cloudy weather has significantly slowed emergence and transplant growth the past few weeks. The longer it takes for emergence and transplants to establish themselves, the more likely they are to pick up pre- and post-emergent damping-off diseases such as Rhizoctonia or Pythium.
- Botrytis is being reported in greenhouse tomatoes and in strawberries fields. The weather the past few weeks has been ideal for its development in a multitude of crops. Growers need to scout on a regular basis and incorporate Botrytis specific fungicides into their weekly maintenance sprays as long as the current weather pattern remains the same.
- Transplant health – transplants that have yet to be put in the field and that are showing signs of stress via the lack of fertility and water to keep them to size can become predisposed to a multiple of opportunistic fungal and bacterial pathogens. Growers need to pay close attention to and adjust fertility and watering programs on a daily basis and consider preventative fungicide applications.
Veg IPM Update: Week Ending 5/11/16
Two-spotted spider mite (TSSM) infestations have recently been discovered in high tunnels.
TSSM feeding results in small white pin-spots on the upper leaf surface (see photos). Mites are actually underneath leaves. These pests can increase dramatically in the warm, dry environment of the tunnel.
Check 5 plants each in 5 separate locations in the tunnel. Inspect the entire plant, and be sure to check the underside of leaves that display the whitish mite feeding. If mites are found, it is best to immediately treat. TSSM is much more easily managed, when the problem is addressed at low levels. If allowed to spread throughout the tunnel, TSSM will be much more difficult to control.
See the 2016 Commercial Vegetable Production Recommendations – Pest Management section for materials that are labeled for use in greenhouse structures, including those that are OMRI approved.
[Read more…]