Vista N.J. 77349 X Julyred. The cross was made in 1956, 

 Bella selected in 1962 and introduced in 1974 by the 

 N.J.A.E.S., New Brunswick. 



Wealthy Originated in Excelsior, Minnesota from a seed of 

 the Cherry Crab planted about 1860. 



Winter Originated as a chance seedling on a farm in Cass 

 Banana County, Indiana about 1876. It was introduced in 

 1890. 



Wisconsin N.J. 148842 X PRI 187--^. The cross was made in 1956, 

 Viking selected in 1963 and introduced in 1969 by the Wis- 

 consin Agr . Exp. Sta., Sturgeon Bay. 



Yellow This variety was imported from Russia by the United 

 Transparent States Department of Agriculture in 1890. 



A********* 



ORCHARD MOUSE BAIT AND THE WEATHER 



Edward R. Ladd 

 Fish and Wildlife Service 

 4 Whalley Street, Hadley, MA 01035 



One of the more common rodenticides used today for the control 

 of orchard mice is zinc phosphide (Zn,P-,). It is a dull gray 

 crystaline material insoluble in water and alcohol, slightly 

 soluble in alkalis and oil and readily degraded under various acid 

 conditions. Because zinc phosphide is more stable under certain 

 conditions than others, the question arose concerning how long it 

 remains effective under various field conditions. 



There are several research findings on zinc phosphide which 

 tends to clarify the question on field stability. 



1. Zinc phosphide kept in a sealed, dry condition should remain 

 stable for 3 or more years. Grain treated baits stored under 

 the same dry conditions should have a similar shelf life. 



2. Grain baits placed out-of-doors under protected conditions 

 can remain toxic for several months. 



3. The use of oils or waxing materials in bait preparations or 

 as an overcoating will extend the field life span of baits. 



4. The major cause of loss in effectiveness of field applied baits 

 is the physical removal of zinc phosphide by rainfall. One 

 inch of rain can remove up to 601 of the toxicant. 



