-7- 



Although statistical differences in shoot hardiness were occa- 

 sionally detected as a result of the application of these materials, 

 the differences were small and of little practical significance. 

 Based,on these 2 years' data, it appears that Alar and Ethrel had 

 only limited and erratic effects in altering the cold hardiness of 

 Mcintosh or Delicious shoots, and the use of these materials probably 

 does not significantly increase or decrease the possibility of low 

 temperature injury, even though they do alter the physiology of the 

 tree . 



**************** 



QUINCE RUST ON APPLE 



Daniel R. Cooley, Extension Technician 

 Plant Pathology 

 University of Massachusetts 



Quince rust (caused by the fungus Gymno sporangium clavipes ] 

 appeared as a problem on Red Delicious in Massachusetts this past 

 season. It was also present in the Hudson Valley area of New York. 

 Generally, the disease is of little importance, but outbreaks can 

 cause serious damage. 



Quince rust shows on the fruit as a sunken, dark green, mis- 

 shapen area near the calyx end. The disease often extends into the 

 fruit, discoloring areas as far as the seed cavities. Fruit may also 

 redden prematurely. The disease seldom affects apple leaves. 



Quince rust is related to cedar apple rust. Both fungi require 

 two hosts in order to reproduce. During July and August, infections 

 on apples (or on related plants, such as quince, hawthome, amelan- 

 chier or crabapple) produce spores. Wind blows these spores to the 

 next host plant, the red cedar or native juniper, where infections 

 are started. After 2 years, wet weather in May or June will release 

 spores from the juniper and red cedar infections. These spores will 

 infect apple or related plants, and the cycle repeats itself. 



Removing red cedars and other junipers located within 2 miles 

 of the orchard makes rust control much easier. Widening the juniper- 

 free area to 4 or 5 miles can completely control rusts. However, in 



most cases, it is more practical to apply a fungicide. A grower 

 should note that while some scab fungicides also provide good rust 

 control (Dikar, manzate, polyram) , other good scab fungicides do not 

 control rust (benomyl, captafol, captan, dodine, glyodin) . Other 



fungicides give good rust control, and fair to poor scab control 

 (ferbam, Niacide-M, thiram, zineb)*. Fungicides to control quince 

 rust and cedar apple rust should be applied from the time of pink 

 buds to the third cover. 



