Issue link: https://read.dmtmag.com/i/298602
44 MAY 1, 2014 GOOD FRUIT GROWER www.goodfruit.com a fungicide that is widely used on stone fruit but that is not labeled on apples. I am aware that other lab-based research has suggested that fenbuconazole (Indar) may also interact synergistically with insecti- cides to harm bees. If current evidence (which is still quite limited) implicates only two from among more than 25 fun- gicide ingredients, then there is no basis at all for the generalization that growers should avoid all fungicides during bloom so as to protect bees. More specificity is required! It would certainly be possible to avoid Indar (and perhaps all of the related DMI fungicides) on apples during bloom if field studies eventually prove that any of these fungicides have a negative impact on bees. However, avoiding bloom-time sprays of chloro- thalonil on stone fruits may be more difficult, at least in nonarid growing regions, because chlorothalonil is a key component of fungicide resistance management strategies for some stone fruit programs. Ultimately, if U.S. Envi- ronmental Protection Agency scientists agree that chlorothalonil can synergize with insecticides and contribute to bee mortality, the next step would presum- ably involve a careful analysis of whether it will be more feasible for beekeepers to find alternative methods for controlling Varroa mite or for stone fruit growers to find an alter- native for controlling fungal diseases that attack stone fruits during bloom. As Dr. Phillip Brannen, tree fruit pathologist in Georgia, suggested in an e-mail exchange on this subject, "This is why God made the EPA." Ground cover Finally, if there is a real concern that fungicides can synergize insecticide toxicity to bees, then we may need to consider impacts of pesticide combinations that are applied before and after bloom as well as those applied when trees are in bloom. There is increasing recognition that wild honeybees and other native pollinators can play a significant role in orchards, especially in eastern United States where smaller orchards are surrounded by unfarmed habitat. However, the ground cover in most eastern orchards contains broadleaved weeds (e.g., dandelion, white clover) that bloom both before and after the orchard trees are in bloom. The impact of pesticides on wild pollinators that visit flowering weeds in the orchards has received scant consideration but could be important for the health of wild pollinators. Furthermore, controlling broadleaved weeds in the orchard ground cover has positive impacts unrelated to the health of wild pollinators. We already know that broadleaved weeds support populations of rosy apple aphid and tarnished plant bug in apple orchards and of cat-facing insects and tomato ringspot virus in stone fruits. Interest in protecting wild pollinators from pesti- cide exposure provides just one more reason for elimi- nating flowering weeds in orchard ground cover. Ultimately, we should all realize that we live and produce food in a very complex, highly interconnected environment. As we gradually increase our understand- ing of that complexity, we may need to change older and previously accepted ways of managing our crops. But precisely because of that complexity, we should reject calls for drastic changes, such as "avoiding fungicides during bloom," until both the need for and impacts of those changes have been fully assessed. • L earn about Dr. Rosenberger's background and research focus at https://pppmb.cals. cornell.edu/people/dave-rosenberger. "This is why God made the EPA." —Dr. Phillip Brannen PHOTO BY GERALDINE WARNER A case could be made for eliminating flowering weeds from orchard ground cover.