season is essential to determine if mites are responding as 

 desired, and to determine timing and choice of any 

 supplemental mite control treatments that may prove 

 necessary. A period of several years may be required to 

 convert from an intensive chemical control program to one 

 based on conservation of mite predators, as predator 

 populations will require time to increase in numbers. This 

 process may be shortened by purchasing and releasing 

 predator mites into orchards lacking predators after 

 predator conservation practices have been established 

 (see, for example, Field et al., 1979). 



References 



Bostanian, N.J. and LJ. Couiombe. 1986. An integrated 

 pest management program for apple orchards in 

 southwestern Quebec. Can. Entomol. 118:1131-1142. 



Butkewich, S.L. and R.J. Prokopy. 1985. Update on the 

 relative toxicity of orchard pesticides to the predator mite 

 Amblyseius fallacis. Fruit Notes 50:9-10. 



Field, R.P., W.J. Webster and D.S. Morris. 1979. Mass 



rearing Typhlodromus occidentalis Nesbitt (Acarina: 

 Phytoseiidae) for release in orchards. /. Aust. ent. Soc. 

 18:213-215. 



Hislop, R.G. and RJ. Prokopy. 1981. Integrated 

 management of phytophagous mites in Massachusetts 

 (U.S A.) apple orchards. 2. Influence of pesticides on the 

 predator Amblyseius fallacis (Acarina: Phytoseiidae) 

 under laboratory and field conditions. Prot. Ecol. 3:157- 

 172. 



McMurtry,JA. 1982. The use ofphytoseiids for biological 

 control: progress and future prospects. In: Recent 

 Advances in Knowledge of the Phytoseiidae, MA. Hoy (ed), 

 Pub. 3284 of the Univ. Cal., 92 pp. 



Thwaite, G. and C. Bower. 1980. Predators spell doom for 

 orchard mites. Agric. Gazette ofN. S. W. 91(4):16-19. 



van dc Vrie, M. and A. Bocrsma. 1970. The influence of 

 the prcdaccous mite Typhlodromus (A.) potentillae 

 (Carman) on the development of/'a/i<?/i>'c/iwjw//m (Koch) 

 on apple grown under various nitrogen conditons. 

 Entomophaga 15:291-304. 



* * * 



Comparing Costs of Rubigan^"^ and 

 Conventional Fungicides 



Daniel R. Cooley 



Department of Plant Pathology, University of Massachusetts 



One of the most appealing features of the ergosterol 

 biosynthesis inhibiting fungicides (Si's) is that they offer 

 longer periods between applications than do conventional 

 fungicides. Rubigan 1 EC^^ at 6 oz/acre, when combined 

 with a half-rate of Dithane M45 80W™ (0.75 lbs/ 100 gal), 

 has performed well when used at 10 day intervals in tests at 

 the Horticultural Research Center, Belchcrtown, MA 

 (Table 1). It should be noted that the performance of 

 Rubigan at the 4-oz rate plus the half-rate of Dithane is not 

 as good, and generally would not be acceptable, at the 10- 

 day intervals. After looking at efficacy, we then examined 

 the economics of a complete-season Rubigan program. 



At 10-day intervals, 6 Rubigan/Dithane applications 

 were used in primary scab season last year (Table 2). At 7- 

 day intervals, 9 standard applications would have been 

 necessary. Looking at fungicide costs, using retail cost 



estimates, we found that the Rubigan/Dithane program 

 was more expensive than a standard program (Tables 2 

 and 3). (The standard program used was 1.5 lbs/100 gal in 

 all applications, plus 2 applications containing 3/8 lb/100 

 gal Cyprex 65W.) 



However, fungicides themselves are only part of the 

 costs. Application costs, such as gasoline, equipment wear, 

 and labor, must also be considered. Since the Rubigan/ 

 Dithane program requires fewer applications, then such 

 costs over a season will be lower. Estimates for application 

 costs vary: in Massachusetts they are estimated at approxi- 

 mately $5.50/acre/application, while in New York they 

 are estimated at $16.00/acre/application. When the non- 

 fungicide costs were varied, and applied to different types 

 of seasons, the following results were obtained (Table 4). 



In a season similar to last season (9 standard sprays vs. 



12 



