12 



]. Oxamyl (Vydate) Program . This program is aimed at control of 

 STLM adults and larvae and consists of 1 application of oxamyl 

 (half strength) at pink directed against 1st generation adults 

 and larvae and/or 1 application (full or half strength) in July 

 against 2nd generation larvae. The latter application should be 

 made only where sap- feeding mines reach or exceed an average 

 of 2 per leaf. Massachusetts has received a special 24 (c) 

 registration for use of oxamyl on bearing apple trees in 1980. 



Inasmuch as oxamyl will not control plant bugs, an additional 

 pesticide should be included in pre-bloom treatments for this 

 purpose. Oxamyl has thinning effects, and should not be applied 

 at pctalfall or for 30 days thereafter. Because oxamyl is sys- 

 temic and has better residual activity than methomyl, timing of 

 application may be somewhat less critical than with methomyl. 

 Also oxamyl may be used with much less risk of phytoxicity than 

 methomyl on early ripening apple cultivars. 



There are 2 major disadvantages of this program. First, oxamyl 

 is an extremely dangerous compound, having caused considerable 

 sickness among a number of Hudson Valley growers in 1979. Its 

 inhalation toxicity is many times greater than that of methomyl. 

 Use of a good respirator and gloves is an absolute must. Second, 

 oxamyl, like methomyl, is highly detrimental to mite and aphid 

 predators, although it may provide some degree of spider mite 

 control during the first years of use before resistance develops. 

 Be prepared for eventual outbreaks of spider mites and aphids if 

 you use oxamyl. 



CONCLUSIONS 



The information gained by New York researchers during 5 years 

 of recent experience with STLM is of im.mense value to our ability 

 to cope with the new insecticide- resistant strains of STLM entering 

 Massachusetts orchards. Several of the possible measures aimed at 

 controlling this pest pose a serious threat to the survival and build- 

 up of spider mite and aphid predators in integrated pest management 

 orchards. However, if growers use discretion in application of 

 measures for STLM control, and employ control measures only when 

 truly necessary and at optimal times, then the chances for success- 

 ful integrated pest management in the future are greater. In this 

 regard, treatments against 1st generation STLM larvae will have much 

 less adverse effect on beneficial predators than treatment against 2nd 

 generation larvae. We must be very careful not to apply excessive 

 numbers or rates of those few materials currently effective against 

 STLM, lest we induce rapid development of STLM resistance to these 

 materials. Further research by colleagues in New York and other 

 surrounding states, coupled with our own studies here in Massachusetts, 

 will hopefully lead to less hazardous and less disruptive means of 

 controlling STLM in the future. 



