Weekend scab and rust infection periods

We recorded three scab and cedar-apple rust infection periods since Friday evening, May 13 (actually each of the last four nights): May 13-14 (14 hr, 63°), May 14-15 (14 hr, 63°), and May 15-16 (17 hr, 64-56°). Total rainfall for these three infection periods was 1.2". All of these were favorable for cedar-apple rust on foliage and rust inoculum is still available. Most fruit were no longer susceptible to quince rust.  These four consecutive infection periods pose a serious secondary scab threat and, because of the difficulty maintaining good spray coverage earlier, it will be important to scout orchards carefully for scab the next week or two to ensure clean fruit.


Since May 8 we now have accumulated 55 hr toward the 250 wetting hour threshold for specific treatment against the sooty blotch and flyspeck fungal complex.