126 JOURNAL OF THE 



be a serious task <.'onipared with the benefit to be derived. I 

 have noticed cabbage-, tomatoes and potatoes, all which are seri- 

 ously susceptible to the disease, growing in an abandoned condi- 

 tion for two months in the latter part of the season, all the while 

 providing for the rapid development and multiplication of the 

 parasites. During this time two successive generations of the 

 worms are developed. Each female egg would, on the average, 

 making no allowance for fatalities, produce in the first generation 

 200 young. Allowing 50 per cent, of these for males there would 

 be 100 to start the second generation for every one at the begin- 

 ning of the first. These w^ould, then, on the basis of a similar 

 computation produce 20,000 young, or 10,000 females to be the 

 producers of the third generation. Then during the time of the 

 abandoned growth of these diseased plants every productive para- 

 site has produced 10,000 productive parasites. 



Treatment of PERENNiALS.^The greatest care should be 

 exercised in the cultivation of perennials like the grape, peach, 

 fig, etc. The young plants should be obtained from sources 

 where it is known they have been grown in non-infected soil. 

 The orchard or grapery should be selected and by a system of 

 cultivation of insusceptible plants be rendered sterile by starving 

 out the worms. Then the practice of cultivating either for forage 

 or as a fertilizer plants liable to the disease in the orchard should 

 be discontinued. Where orchards or graperies are so seriously 

 injured as to interfere with the productiveness of the trees or 

 vines they might be preserved for a few years while the orchard 

 is renewed in soil freed from the worms, when they should be 

 destroyed. 



The peach-trees and grape-vines which I have examined in 

 the vicinity of Auburn, while slightly affected do not appear yet 

 to suffer any serious consequences. Young tree and seedlings 

 are more seriously affected. The most badly diseased grape cut- 

 tings I have seen were those grown very near diseased cabbages 

 and tomatoes. Care should also be used in the cultivation of 

 seed potatoes which are not infected. 



