operating at 2.5 miles per hour. Treatments con- 

 sisted of either a single application at tight cluster 

 or two applications in various combinations of oil 

 and Apollo at 1/4-inch green and tight cluster. Ma- 

 terials were applied as outlined in Table 1 under 

 calm conditions. 



European red mite populations were evaluated 

 periodically by selecting 15 leaves per tree randomly 

 from each of four trees per treatment. Composite 

 samples then were brushed on to glass plates, and 

 mite populations were estimated using standard leaf 

 brushing protocol. Results were recorded as motile 

 forms per leaf. 



Results & Discussion 



As would be expected, all four treatments sup- 

 pressed early season ERM buildup when compared 

 to the check (Figure 1). Mite populations increased 

 rapidly where no prebloom treatments were applied 

 so that intervention with summer miticides was 

 warranted by late June. Data collection was dis- 

 continued once mite populations exceeded thresh- 

 old levels and "rescue" treatments were deemed 

 necessary. 



The split treatment of oil alone and the Apollo 

 treatment at tight cluster provided similar results. 



Both these treatments effectively controlled ERM 

 populations until approximately mid July. The rela- 

 tively high counts recorded on July 20 consisted 

 mostly of recently hatched njTnphs that did not re- 

 sult in excessive foliar damage before a contact miti- 

 cide could be applied. These results are consistent 

 with the effect observed most years when growers 

 apply the two-oil-spray program. The single appli- 

 cation of Apollo at tight cluster was able to dupli- 

 cate these results. 



The most effective ERM suppression observed 

 in this trial was noted in the oil followed by Apollo 

 plot and the oil followed by oil plus Apollo plots. 

 Little difference was noted between these two plots. 

 Both of these regimes were able to keep red mite 

 populations below troublesome levels for the entire 

 growing season. ERM counts averaged approxi- 

 mately 6 per leaf in late August so that no summer 

 contact miticides were necessary. Foliar condition 

 was excellent in both plots, with only minimal bronz- 

 ing of fruit spurs low and inside the tree canopy. 



Conclusions 



While it is difficult to draw firm conclusions ft"om 

 a single non-replicated study in any given year, the 

 data presented here suggest that the inclusion of 



« 



3 



s 



- no trt / Apollo 

 -oil /oil 

 'Oil /Apollo 

 -oil / oil > Apollo 

 -check 



Figure 1. Effects of Apollo alone and in combination with dormant oil on Euro- 

 pean red mite populations. 



Fruit Notes, Spring, 1996 



15 



