Heavy scab and rust infection period in progress May 7

Since yesterday morning at 10 AM we have had 24 hr wetting at 54-56°, almost optimum for apple scab, quince rust and cedar-apple rust. Blossoms at petal fall are still very susceptible to quince rust infection so a follow-up including an SI fungicide in the next application is highly recommended (a "no-brainer"). Regarding potential rust inoculum source, winds during the wetting since yesterday have been from the north and east and appear to continue this way through today and tonight, then shift to a more southerly direction with continued shower activity tomorrow.

This will be a pivotal point in this year's scab epidemic. We will soon be nearing the end of predicted primary ascospore discharge, but lesions from our first infection period Apr 17 are expected to be appearing this week. So where control was good for the previous infection periods, we won't have too much to go till we can begin to focus on summer disease control, but where earlier control was inadequate, this infection period will be the source of continued headaches throughout May.

Yesterday was one of those unusual exceptions where there wasn't a forecast for rain early in the day, even with the Weather Channel's hourly predictions while it was raining! Today's SkyBit hourly report for our AREC for yesterday does not show leaf wetness until 4 PM but we had leaf wetness with showers at 10 AM, and leaves have probably remained wet since then.

I usually try to focus on our Winchester situation, where we have a better record of weather conditions, but it appears that those of you east of the Blue Ridge and farther south had similar conditions and substantially more rain than we did yesterday. Hopefully apples a little more advanced, with fruit at thinning time will be less susceptible to quince rust, but any trees with some blossoms in recent petal fall should be considered susceptible, and scatterred quince rust-infected fruits can hang on the tree and become a nuisance as a rot inoculum source as shown in the what-is-it blog below:  http://treefruitdisease.blogspot.com/2013/04/what-is-it-april-4-meeting-reminder.html