48 STATE HORTICTILTTTRAL SOCIETY. 



and must use more fertilizer than is necessary for fruit production alone. 

 Good plants are produced only by specialized and intensive means, 

 which makes their production more expensive. 



These are, briefly, some of the reasons why it pays to purchase good 

 nursery stock and thereby be sure of getting plants that are true to 

 name, vigorous, free from disease, and carefully grown, handled and 

 packed. They will give you satisfaction. 



PARADICHLOROBENZIXE FOR PEACH TREE BORERS. 



G. E. WILSON, ST. JOHNS, MICHIGAN. 



For several years experiments with soil fumigants have been under 

 way. Sodium cyanide was among the first that were used, but this 

 is dangerous to the tree and it is also very dangerous to man. In 1919-20, 

 the first use of paradichlorobenzine was made by tlu> U. S. Department 

 of Agriculture and the New Jersey experiment station. The work was 

 first started in Michigan in 1920. This year, 1921, saw its use in six 

 counties. 



Paradichlorobenzine is a white, crj'stalinc substance, insoluble in 

 water, and the evaporating gas is heavier than air. It is not dangerous 

 to man, but it causes death to the peach borers. 



It will be necessary for clearness to discuss the subject under six 

 points, first of which is that it can be used safelj^ on trees six years old or 

 older, and though no definite recommendations are made for youngei- 

 trees, it is probable that a way will be found to use it on trees as young as 

 three j-ears. 



The second point to be observed in the treatment is the amount of 

 the substance applied. This varies from % to 1 ounce on the oldei' 

 trees and 3^ to 1 ounce on the younger trees, with a short exposure of 

 10 to 14 days. In the work done to date, none of the varieties of peaches 

 seem to be injured by the treatment. The crytals should be finely 

 powdered, passing through a ten mesh screen or finer, for, the finer the 

 crystals, the more surface area, and consequently a greater rate of evap- 

 oration. When injury occurs, the growing portion of the tree, or cam- 

 bium layer, is dotted with fine brown spots which eventually converge, 

 the bark shrivels, and the tree dies. 



A third point to be remembered, and one that is very important, is the 

 preparation of the tree prior to the application. All of the refuse around 

 the base of the tree should be removed to the bare ground, being careful 

 not to disturb the top soil thereby creating air pockets in which the 

 gas will collect, making the results unsatisfactor3^ If there is a large 

 quantity of gum exuding from the tree a few inches above the ground 

 level, it is advisable to build the ground level up to this point, and to 

 remove the gum before making the application. In case this is done 

 the ground should be well packed. 



The fourth point to be kept in mind is that the paradichlorobenzine 

 crystals should be distributed in a continuous circle, one inch wide 

 and the center of which is two inches from the trunk of the tree. In 

 covering the crystals, the first soil should be sifted on so that the crystals 

 will not l)c disturl)ed. The rest of the soil can be shoveled on and mound- 

 ed up around the tree. This mound should be well packed with the 

 back of the shovel or any other implement for tamping soil. 



