-18- 



1.81 injury from SJS in 1981 after a concerted effort by field 

 staff and the growers to accurately time sprays with regard to 

 observed stages of SJS development. 



Plum curculio injury was substantially lower than in 1980, 

 amounting to 0.61, 0.74 and 0.47% injury in Previous Year IPM, 

 First Year IPM and check blocks respectively. PC injury in most 



injury 



Injury from European Apple Sawfly (EAS) , Apple Maggot Fly 

 (AMF) , Codling Moth (CM), White Apple Leafhopper (WAL) , Green 

 Fruitworm (GFW) and Leafrollers (LR) was relatively low in all 

 blocks. Total injury from these pests averaged 0.28, 0.35, and 0.75% 

 in Previous Year IPM, First Year IPM and check blocks respectively. 



One block of 5 year old "spur-type" Cortlands on M7 experienced 

 substantial injury from first generation European Corn Borer (ECB) . 

 This was observed during the course of grower hand- thinning of 

 fruit, although no injury from ECB was found at harvest. This is 

 perhaps because hand thinning removed the protected feeding sites 

 within fruit clusters on spurs, and aided in spray penetration and 

 control. It is also possible that sprays against apple maggot killed 

 second generation ECB adults or that mowing of tall grasses and weeds 

 near the trees deprived ECB adults of egglaying sites. 



Mite Populations - 1981 marked a partial resurgence of popu- 

 lations of Amblyseius fallacis , our major predatory mite. It was 

 found in relatively high numbers (> 0.4/leaf) in 8 IPM blocks in 

 1981, while no A. fallacis were found in check blocks (Table 2). 

 This compares to 1980, when predator numbers were extremely low 

 throughout the state, perhaps due to high overwintering mortality 

 resulting from lack of snow cover. 



With a few exceptions, spider mites were more easily controlled 

 in 1981 than in other years, although some blocks, especially those 

 with normally troublesome cultivars such as 'Puritan' and 'Delicious' 

 required repeated treatments. Other blocks, several of which had 

 required miticides in the past, needed little if any miticide. 

 Heavy oil use directed at San Jose Scale may have contributed to 

 this latter phenomenon. In addition, heavy rain showers in May, 

 June and July may have contributed to the fewer than usual mite pro- 

 blems in 1981. 



Insecticide, Aphicide and Miticide Use . 



Previous Year IPM blocks (averaging 7.95 sprays, range 3 to 11) 

 and First Year IPM blocks (averaging 7.57 sprays, range 5 to 10) 

 received 23% and 26% fewer insecticide applications, respectively, 

 than check blocks (average 10.28 sprays, range 8-13) (Table 3). 



