We have had quite an infection period starting Monday morning and hopefully
ending this afternoon, April 29th. If leaves remain wet into nighttime, these
hours are added to the infection period, making the infection period even more
significant. This is a huge infection period, probably releasing 50% of all
ascospores for the primary scab season. Hopefully everyone applied a fungicide
within a few days before the infection period.
An additional concern is whether or not more spores matured during dry spells yesterday and today. These spores were then released onto foliage potentially unprotected because of so much rain washing off the fungicide. Where scab was a problem last year, it is probably a good idea to spray a fungicide with kickback as soon as possible – probably on Wednesday. Fungicides with kickback include Flint, Sovran, Scala, Vangard, and Syllit. The SI fungicides, Rubigan and Nova, can be used if you don’t suspect resistance. Actually rather than use one of these 2 SI’s, it would be better to use one of the new SI’s, Indar or Inspire.
Growers with little or no scab last year, probably need not worry about an additional infection period on Tuesday, April 29th.
Just a reminder, we won’t see lesions from this infection period for about 2 weeks, or until May 13.
I expect we will be into early bloom later this week. And the long range forecast does not include extremely hot weather. This is a good thing. Last year we ran into trouble with fire blight when we had hot and humid weather during bloom.
If you did not get a chance to apply a prebloom oil, or you feel it was inadequate, you can apply Apollo, Savey, or Zeal before bloom or at petal fall. Another alternative is to apply Agri-Mek within the first two weeks after petal fall. Agri-Mek applied at this time will also control leafminer. Agri-Mek must be applied with oil or some other surfactant to penetrate the leaf surface.
Next message will be recorded Tuesday, May 6th.