Effects of the Loss of EBDC Fungicides on 

 Apple IPM in New England 



Daniel R. Cooley 



Department of Plant Pathology, University of Massachusetts 



Stephen Wood 



New England Fruit Growers' Council on the Environment 



John Schneider 



Very fine Products, Inc., Technical Department 



Over the past several years, fungicides have been 

 the subject of steadily increasing criticism from food 

 safety advocates. At the moment, they are also in the 

 center of EPA's limelight. 



Many of the fungicides New England growers rely 

 on to control diseases in fruit crops are thought to have 

 the potential to cause various chronic, human-health 

 disorders. As a result, growers have cause to wonder 

 about the future of the fungicides they now use. Some 

 may soon be regulated off the market, some may be 

 dropped from the market by their manufacturers, and 

 some may be driven from the market by another explo- 

 sion of public emotion. 



Right now, the fungicides at center stage are the 

 ethylene bisdithiocarbamates (EBDCs) which include 

 all formulations of maneb (Maneb™, Dithane M-22™, 

 Manzate D™, Manex™, etc.), mancozeb (Dithane M- 

 45™, Manzate 200™, Penncozeb™, Dikar™, etc.), 

 metiram (Polyram™, Zinc-metiram™, etc.) and zineb. 

 Anticipating a recommendation from EPA that future 

 use on apples be forbidden, the registrants of all EBDC 

 fungicides agreed to drop apples from the 1990 label. 

 This measure presents growers with the problem of 

 producing next year's crop, and possibly every crop 

 thereafter, without EBDC fungicides. 



This paper attempts to describe the effects of the 

 loss of EBDC fungicides on IPM fruit growers in New 

 England, and more generally to explain the extent to 

 which successful IPM depends on the continued availa- 

 bility of a broad variety of similar fungicides. 



Most older fungicides (registered before 1970) are 

 under fire for their potential to cause cancer, tumors, 

 reproductive disorders, or a variety of other chronic 

 health problems. Under the present regulatory 

 scheme, the EPA attempts to determine which com- 

 pounds with similar uses present the lowest theoretical 

 risk. In a given group of materials with similar uses, 

 the compound with the lowest risk is cleared for contin- 



ued use, while the "more hazardous alternatives" are 

 disallowed. Certain proposed legislation is intended to 

 compel EPA to take this approach. 



The problem with this approach, from an IPM 

 grower's perspective, is that it will hamper the ability 

 to be precise. There is no "all purpose fungicide." 

 While it is useful conceptually to think of benzim- 

 idizoles or EBDCs as apple scab fungicides, each com- 

 pound has specific properties which make it the most 

 appropriate material to use under a given set of cir- 

 cumstances. IPM growers make pesticide use deci- 

 sions that are highly specific to the exact combinations 

 of diseases, arthropods, stages of tree development, 

 and environmental conditions present in their or- 

 chards at given times. Growers also specifically apply 

 fungicides to different pails of the orchard, depending 

 on cultivar or tree size. Without a wide variety of 

 chemicals from which to choose, such precision would 

 be impossible. In fact, a reduction in the number of 

 available fungicides will limit precision rather than 

 lowering the volume of fungicide used. The hard fact is 

 that two compounds that control the same disease 

 virtually never have the same full range of effects. 



Without EBDCs next year, New England IPM 

 growers will experience a painful example of this limi- 

 tation. Assuming for now that no EBDCs will be 

 available for use on apples in 1990, our toolbox for next 

 year will contain the following fungicides. 



Bcnomyl (Benlate™) 



Captan (Captcc™, Orthocide™) 



Dodine (Cyprex™) 



Fenarimol (Rubigan™) 



Ferbam 



Fixed coppers (Kocide™, COCS™) 



Myclobutanil (Nova™) 



Sulfur 



Thiophanate-methyl (Topsin-M™) 



Thiram 



Triforine (Funginex™) 



Fruit Notes, Winter, 1990 



19 



