November 1941 y/ ■ n © n\ E-555 
 
 EFFECT OF ETHYLENE DICHLORIDE EMULSION ON PEACH TREES 
 
 By Oliver I. Snapp, 
 Division of Fruit Insect Investigations 
 
 Following the announcement of the ethylene dichloride treatment 
 for peach borer control, a large number of growers in many parts of the 
 country have adopted this new method and have used it very successfully 
 for the control of the peach borer. Literally hundreds of thousands of 
 peach trees have been treated, and for the most part no damage has occurred. 
 During 1940, however, the death of considerable numbers of trees and serious 
 injury to others which occurred in the Middle Appalachian region was attrib- 
 uted to the use of ethylene dichloride. A careful investigation of the situ- 
 ation revealed the fact that much of the reported injury was actually caused 
 by winter conditions. In many cases there was just as much injury in or- 
 chards not receiving the ethylene dichloride treatment as there was in similar 
 orchards nearby which had received the chemical. In a very few cases, how- 
 ever, the emulsion was used at excessive strengths or in other ways not in 
 accordance with recommendations, and in such cases some of the injury re- 
 ported was undoubtedly caused by the chemical. 
 
 As a result of these reports further investigations are being carried 
 on by State and Federal workers to determine the conditions under which 
 injury is most likely to occur. This work is still in progress, and final 
 conclusions have not yet been reached. However, a brief statement on the 
 present trend of the results can be made. It appears that the danger of 
 injury is least in light sandy soils. Experimental treatments with the pure, 
 undiluted ethylene dichloride caused little or no injury to young and bear- 
 ing trees in light sandy soils during the season of 1940-41. The narrowest 
 margin has been found in certain rather heavy types of soils, and there may 
 be very exceptional types of soil in which the usual treatment may cause 
 injury. Considerable injury has also developed from the application of doses 
 in excess of those recommended, to trees in water-logged soil in late fall 
 at low temperatures. Whether the water-soaked condition of the soil, the 
 low temperature, or the two together were responsible has not been deter- 
 mined. 
 
/ERSITY OF FLORIDA 
 
 3 1262 09230 4061 
 
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 The investigation has emphasized further the need for strict ad- 
 
 .. d e d the quantities applied should not be greatly in 
 Ses^of tht —ended. The e,.ulsion should be a very stable one and 
 shouW be frequently stirred with a paddle before any is taken out This 
 appl «s both To the "stook emulsion and to the diluted mixture. The materia 
 should not be poured direotly on the trunk, but should as far as possible be 
 applied to the soil close to it.