How Good is Provado™ Applied at 

 Petal Fall in Controlling Leafminers 

 and Leafhoppers? 



Ronald Prokopy, Jennifer Mason and Starker Wright 

 Department of Entomologyy University of Massachusetts 



In 1995, a new insecticide called Provado''''^ 

 (common name imidacloprid) received a label for 

 use in controlling leafminers, leafhoppers, and 

 aphids on apple trees. Researchers in New York 

 have tested Provado for several years in experimen- 

 tal apple tree plots and have concluded that it has 

 excellent potential for controlling these three foliar 

 pests of apple. Fortunately, it appears to have rela- 

 tively little negative effect on beneficial predators 

 of mites and aphids. 



Prior to 1995, we in Massachusetts have had 

 no experience with Provado as an orchard insecti- 

 cide. Here, we provide data on the effects of a single 

 petal-fall application of Provado against leafminers, 

 white apple leafhoppers, and rose leafhoppers. We 

 did not design tests specifically to evaluate effects 

 of Provado against these pests. Rather, the oppor- 

 tunity to gather meaningful data arose during the 

 course of experiments aimed at studying immigra- 

 tion patterns of rose leafhoppers into commercial 

 orchards. 



Materials & Methods 



In Orchard A, four plots of semi-dwarf trees re- 

 ceived a grower-applied spray of Provado at petal 

 fall at a rate of 2 ounces per 100 gallons (6 ounces 

 per acre). Four nearby similar plots received no 

 Provado. No other leafminer-controlling pesticide 

 was applied to any of the plots. On July 31, we 

 examined ten randomly selected leaves on each of 

 the five trees in each plot for evidence of leafminer 

 mines. 



In Orchards A, B, and C, eleven one-half-acre 

 blocks of semi-dwarf trees received a grower- applied 

 spray of Provado at petal fall at the above rate. In 

 Orchards D, E, and F, eight similar blocks received 

 no Provado at petal fall. None of these 19 blocks 

 received any other insecticide aimed at controlling 

 leafminers. All were treated with an application of 

 Sevin as a thinning spray during the last week of 



May. None received Sevin thereafter and none re- 

 ceived Thiodan or any other insecticide directed 

 against leafhoppers or aphids. During the first week 

 of June, we hung four yellow sticky traps in each 

 block to monitor numbers of rose leafhopper adults 

 immigrating from patches of rose bushes within 50 

 yards of the block perimeter. We counted captured 

 adults during the fourth week of June. During the 

 third week of July, we counted the number of rose 

 leafhopper nymphs and white apple leafhopper 

 nymphs on ten randomly selected leaves on each of 

 five trees per block. We did the same for leafminer 

 mines during the first week of August. 



Results 



Significantly more (22 times more) combined 

 first- and second-generation leafminer mines were 

 found in untreated than in Provado-treated plots of 

 Orchard A (Table 1). Similarly, significantly more 

 (27 times more) first- and second-generation 

 leafminer mines were found in untreated than in 

 Provado-treated blocks in Orchards A-F (Table 2). 



Almost identical numbers of rose leafhopper 



Table 1. Effect of a petal fall application of 

 Provado on apple blotch leafminer larvae in 

 Orchard A. 



Treatment 



Mean number 

 combined first- and second- 

 generation mines per leaf* 



Provado 

 No Provado 



0.05b 

 1.09a 



* Means followed by a different letter are sig- 

 nificantly different at odds of 19:1. 



Fruit Notes, Fall, 1995 



