-2- 



iods occur, even a slight eunount of inoculum in the orchard is likely to 

 prove hazardous. 



At present, many orchards in the state show a heavier carry over 

 of the scab fungus than usual, for the reason that some growers "let up" on 

 spraying last summer when the season was dry. As one result, there develop- 

 ed more storage scab last winter than has been seen for several years. 

 Another result is an abundance of old, spotted leaves in the orchard liter- 

 ally loaded with ripe ascospores ready to "shoot" during the next rain, 

 Scab spore development in the old leaves is as far advanced as fruit bud 

 development. Heavy discharges will occur in all orchards during the next 

 few wet periods. Hence, the pre-blossom sprays of sulfur are likely to be 

 vejy important on scab-susceptible varieties. 



With the season so far advanced, long, cool, damp periods are likely 

 to be encountered before blooip, and certaiftf^^ttal-f all. Special considera- 

 tion might well be given to the prospective need of dusters (or sprayers in 

 the absence of dusters) during rainy periods. This holds true especially 

 during the blossom period when spore dissemination for both scab and the ce- 

 dar rusts reaches its peak. 



Infection Periods to Date. - So far (April 11) there has been only 

 one infection period for apple scab. The rains on April 2 and 3 furnished an 

 intermittent wet period of about 22 hours in jimherst at an average temperature 

 of around 56° F. Although this was longer than necessary for infection to 

 occur at that temperature, the spore discharge was very light. Fruit buds 

 were betvreen delayed dormant and pre-pink. Only a very light infection is 

 expected from that wetting. The next rain on April 4-5 caused a heavier 

 spore discharge, but the 15 hour period of wetting was too short to allow 

 scab infection at the prevailing temperature of about 43° F. It was during 

 that rain, with fruit buds in early pre-pink, that cedar-apple rust spore 

 horns first underwent gelatinization and discharged spores. The first spore- 

 shower from quince rust cankers is yet to come, but it will occur during the 

 next rain. 



— 0. C. Boyd 



PASTE SULFUR m THE SPRAY IIIG SCHEDULE 



Paste sulfur has been both praised and condemned. It has been praised 

 for its excellent fungicidal properties and scab control; condemned because it 

 is difficult to handle. Paste sulfur is the finest particle sulfur of the wet- 

 table sulfurs, and in this respect comes closest to the spray residue result- 

 ing from liquid lime sulfur; but, in contrast to the liquid, paste sulfur em- 

 bodies all of the safe features of the mild or dry wettable sulfurs. 



Paste sulfurs derived from the gas production industry contain from 

 40-50^ active sulfur. The balance is essentially water. ?/ith the inherent 

 advantage of extremely small particle size, paste should be used at no more 

 than 10 lbs. to 100 gallons of water, and this maximum amount should be 

 limited to the early critical sprays. For the finishing off applications 

 toward the end of the season, the amount can be reduced to 5 lbs. Thus, in 



