Apple Scab Control with Urea.
Video link: http://youtu.be/8g0WyVi68GM

This past season we saw elevated levels of apple scab in southern counties. Our IPM scouts found low levels of scab present in orchards where scab had not been detected for many years, even though these orchards had been carefully sprayed using effective materials. Most likely what we are witnessing is the result of an increasing pattern of wet seasons with periods of extreme rainfall and not resistance to DMI fungicides, although that is an area of great concern and cannot be ruled out. Regardless of the cause, high inoculum in the orchard will eventually lead to control failures with materials such as the DMI’s and other chemistries prone to resistance.

At any rate growers that had scab this year should integrate sanitation practices into their scab control program. The recommended sanitation program involves either: fall or spring applications of Urea; flail mowing fallen leaves: or preferably both.

Dr. Dan Cooley and Jon Clements at UMass have uploaded a short video explaining this approach.

The Cougar Blight model at NEWA is predicting “Extreme Risk” for fire blight for the period May 10-15. The model is basing the prediction on the current weather forecast for both southern and northern regions. Keep a close eye on the weather. Apply antibiotics such as Streptomycin, Mycoshield, or Fireline. Streptomycin is the most effective of the antibiotics. The Terramycin products (Mycoshield and Fireline) should be rotated with strep for resistance management. See the New Jersey Commercial Tree Fruit Production Guide for rates. Keep in mind that these antibiotics are best applied under slow drying conditions (dilute applications), and have limited residual activity.

The Cougar Blight model at NEWA is predicting “Caution” for all Apple and Pear blocks with open blossoms starting May 7. The model is basing the prediction on the current weather forecast for both southern and northern regions. Keep a close eye on the weather. If conditions for infection occur (60°F or above with rain or severe weather including high winds) apply antibiotics such as Streptomycin, Mycoshield, or Fireline. Streptomycin is the most effective of the antibiotics. The Terramycin products (Mycoshield and Fireline) should be rotated with strep for resistance management. See the New Jersey Commercial Tree Fruit Production Guide for rates. Keep in mind that these antibiotics are best applied under slow drying conditions (dilute applications), and have limited residual activity.

In southern counties there is a significant risk for fire blight from Thursday through the weekend for any Pear or Apple orchards with blossoms open. If your orchards are at risk apply antibiotics at the first opportunity. The forecast rain will also be the first significant scab infection for apples. Growers can personalize their risk by visiting the NEWA website. Enter your zip code and follow the links for fire blight and apple scab. You will be prompted to enter phenology information for your location. Using April 6th for  50% McIntosh green tip, the model indicates approximately 40% ascospore maturity on April 20th for South Harrison Township Gloucester County.