Professor and Area Fruit Agent
Are you using our new Cornell NEWA http://newa.cornell.edu/ scab prediction system? Rutgers Cooperative Extension has been a partner with Cornell for the past two years to bring this weather system with disease forecasting to you. NEWA Apple Disease Models
Note: Adequate hours of wetting have occurred for apple scab infections to occur.
Visit the NEWA site &/or browse through the materials found on the Snyder Farm Weather-Pest Forecasting Portal - including instructions in an online Slide Viewer, a downloadable PDF instruction file, as well as an information poster. You can also navigate to the site from the top menu of this blog.
The apple scab forecaster is found at http://newa.cornell.edu/index.php?page=apple-diseases - Locate the closest NEWA station to you and then use the pull down menus. You will need to know your date of Green Tip to look at the forecaster.
On McIntosh, I was at Green Tip Sunday 4/7 at the Rutgers Snyder Farm, Pittstown, NJ. We have our own NEWA weather station there.
Note that adequate hours of wetting occurred Wednesday, April 10, and today, April 12 for apple scab infections to occur. Mike Fargione at Cornell indicates :
"A review of the hourly leaf wetness data for some NEWA stations (using http://newa.cornell.edu/index.php?page=hourly-weather ) and the Mills table (http://ipmguidelines.org/TreeFruits/Chapters/CH06/default-2.aspx ) also supports the possibility of infections based on split wetting periods, even when you don’t count nighttime wetting hours on Wednesday morning (rain began after dark). "The conservative conclusion is that scab infections may have been possible April 11 where adequate green tissue was exposed.
Select the weather station closest to you for the latest weather data and forecasts. The weather is drawn from the national weather service NOAA system http://nws.noaa.gov/
See the previous article on Apple Scab control in this blog.