Both blocks received a Manzate application a week later during late Bloom and captan at Petal Fall. It is interesting to see that the two blocks have a striking difference in the incidence of cedar apple rust lesions on the foliage. The fungus that causes quince rust is in the same genus as the fungus that causes cedar apple rust, but unlike CAR, the QR fungus does not cause leaf infections. These galls swell during wet spring weather and release spores that can infect the apple fruit. Quince Rust Lesion on the Calyx end of Red Delicious.
Trees can decline over several growing seasons.
Again, the rain we had last autumn associated with the hurricane plus the rains this spring provided conditions favorable for infection. Table 6 on page 21 of the 2000-2001 New England Apple Pest Management Guide lists characteristics of a number of rootstocks. Please note that the Guide also provides information on fungicide options, such as Ridomil and Aliette. They will not 'revitalize' trees showing moderate to severe disease symptoms. As mentioned in the last issue of the newsletter, based on the assumption that most of the inoculum for flyspeck infections comes from conidia produced on wild hosts surrounding the orchard, summer fungicides for controlling flyspeck are not needed until 270 hours of wetting have accumulated from 10 days after petal fall.