SusceptJTjl H t./ of Ap-ple Varieties 



Jo variety of apple is immune to poi/dery mildei'j Ijut some are more susceptitle 

 than others and a fevi are highly resistant. 



Relatively resistant varieties are Mcintosh, Delicious, and Golden Delicious. 

 Very susceptible are Baldwin, Cortland, Gravenstein, Eome, Jonathan, Stayman, and 

 Yellow Transparent. 



Sufi:i£:estlona for Control 



Best results are obtained vjhen cultural practices, mechanical means, and 

 chemical treatments are used together. 



(1) Buy and plant only nursery trees that are free from mildew. The nurseryman 

 should control diseases in the nursery hefore he sells the trees to you. 



(2) Prune out all infected terminals during Tjinter pruning and newly infected 

 terminals in summer as far as is practical. This will help keep the fungus 

 from "building up. There is no need to turn the prunings since the fungus 

 will die as soon as the pruned twigs die. 



(3) Spray: There are two materials that will control mildew - sulfur and kara- 

 thane or mildex. Sulfur is a little less expensive and is ciuite satisfactory 

 in the pre-hloom sprays on varieties that are not sensitive to sulfur. In^ 

 jury may result if temperatures are 85° F. or higher after application. Three 

 pounds in 100 gallons is sufficient. 



Karathane is a little more expensive and is preferred in pre-hloom sprays 

 on sulfur sensitive varieties and in the cover sprays on all varieties. It 

 may cause injury when temperatures are 95° ^' 0^ higher for prolonged per- 

 iods. It will cause injury with oil and oil-containing formulations and may 

 cause injury when comhined with organic phosphate insecticides especially 

 during the calyx to second cover period. Other-'ise karathane is compatihle 

 with the common fungicides and insecticides. It even has some miticidal value 

 and will aid in mite control. It is used at 1 Ih. per 100 gallons for the 

 "best mildew control. 



The following points ahout spraying should he kept in mind. 



(1) Start control immediately when mildew is fo\xnd in an orchard. 



(2) '\'here mildew was present the previous year, hegin control "before hloom 

 and continue during the cover periods to avoid huild-up in the "buds and 

 winter carry-over. 



(3) Spray thoroughly so that the mildew is wet "by the spray. 



(k) Use a wotting agent to get good wetting of the f\ingus. Some fungicides, 

 like glyodin, already have enou4?h wetting agent for this purpose. 



C. J. Gilgut 



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