Apple Scab: Well, it sure has been dry! Last week it looked like it would rain all this week – wrong! Without rain there has been no need for a fungicide application for apple scab. That being said, even if we don’t get rain, Dave Rosenberger from Cornell recommends applying a fungicide at pink, regardless of whether or not we get rain. You can read his article on Scaffolds at http://www.nysaes.cornell.edu/ent/scafolds/2008/
Briefly, he states that while the buds are at pink, a fungicide can cover the stems and sepals. When the flowers open, the petals block where the fungicide can be distributed. So if you wait till bloom to spray and there is an apple scab infection period during bloom. You would not be able to protect all scab susceptible surfaces. So, if this dry weather continues and you don’t spray a fungicide, apply a fungicide at pink regardless of the weather.
When we do get rain, an awful lot of spores will be discharged. New York reports that 40% of overwintering spores are mature and ready to be discharged.
Oil: The last several days have been ideal for applying oil to kill mite eggs. I hope many growers have taken advantage of the warm, mostly calm days. Since McIntosh trees are at the tight cluster bud stage, reduce your oil application to 1 gallon oil/100 gal water. Oil can be applied up until the pink stage.
Tarnished plant bugs: I did set up a few TPB traps. I have caught a few TPB, but not many. I did see some buds that are oozing a drop of liquid. This is most probably due to TPB feeding. I have not seen many of these buds and I do not recommend an insecticide at this time.
Leafminers: I have not seen any leafminer adults flying, but there should be some out there. Rather than spray prebloom for leafminers, it is better to wait and see if mines appear after petal fall, and then treat if needed. Leafminer parasites can control many of the leafminer mines, especially if no prebloom insecticide is used.
There is so much to look at on Orchard Radar. Take a look at www.uri.edu/research/ipm
Next message will be recorded 4/29 and emailed 4/30.