February, 1909,] 



165 



Plant Sanitation- 



which at the same time will be a wise 

 procedure owing to there being a certain 

 amount of risk in burning the bushes 

 by saturating them with the liquid 

 at its usual strength. Further, if this 

 thorough style of spraying be carried 

 out, I think it will be found that very 

 much less money will be required for 

 collecting the insects by hand. 



This manner of spraying should be 

 done at least twice in the year if not 

 more frequently, and if one application is 

 not found sufficient— at the usual time 

 after pruning when the bushes are first 

 breaking out, and again, if one necessary, 

 about one month afterwards. So soon 

 as the insects are noticed to be feeding 

 and are about in any numbers, then is 

 the time to spray thoroughly without 

 sparing the liquid. 



An Important Point. 

 An important point to observe in deal- 

 ing with an epidemic of this kind is to 

 thoroughly treat the whole of the 

 affected area in the space of a few days, 

 as the quicker the " round " of the garden 

 is made, the more thorough check will 

 it be to the deposition of eggs. 



In the life-history of the Tea Mos- 

 quito it may not be known that the 

 feeding period of an individual lasts 

 for 2| months. 



Without taking into consideration 

 the hybernating period of the insect 

 during the cold weather months, mature 

 or winged individuals kept in captivity 

 in the Insectarium at Kanny-Koory, 

 lived for 62 days, and if we add to this 

 the period spent in the immature or 

 larval form, which is roughly 10 days, 

 we find, at the height of the season, a 

 single insect lives for quite two-and-a- 

 half months. Add to this the fact that 

 an insect will make as many as 125-150 

 punctures in the leaves every 24 hours, 

 and the damage done to the bush can be 

 imagined.— The World, December, 1908. 



DEVELOPMENT OF DISEASE- 

 RESISTANT VARIETIES 

 OF PLANTS. 



By H. S. Jackson, Newark, Del, 

 [Given before the Massachusetts Horti- 

 cultural Society, March 14, 1908.] 



While the subject which I have 

 selected may not be of special local 

 interest, I believe it to be of sufficient 

 general interest to merit a discussion 

 before any body of men interested in 

 any branch of agricultural science. In 

 the entire discussion of the development 

 of disease-resistant varieties, I may not 



mention any special crops which are of 

 particular interest to Massachusetts 

 Horticulturists, for this phase of plant 

 breeding is not sufficiently developed as 

 yet to enable us to direct the grower 

 how to proceed to obtain results, except 

 with very few crops. The study of the 

 development, by man, of disease resist- 

 ance in plants is yet in its infancy. I 

 propose to discuss the subject in general, 

 and to give a review of what has already 

 been accomplished by horticulturists and 

 plant- breeders in developing plants 

 resistant to specific diseases. 



We must first get a definite idea of 

 what is meant by disease resistance in 

 plants. We must distinguish it from 

 hardiness. Hardiness is a general term. 

 A. hardy variety, as generally considered, 

 is merely one that is less susceptible to 

 cutting frosts, drought, or extreme 

 changes in temperature ; in short, one 

 that is capable of withstanding adverse 

 climatic conditions in a state of health. 

 A disease-resistant variety for our 

 present purpose may be defined as one 

 that shows resistance to the attack of a 

 specific disease due to a specific 

 organism. 



In this age of intensive agriculture, 

 with our advanced and increasing 

 knowledge of the principles of culture 

 and fertilization of all sorts of agri- 

 cultural crops, the question of the health 

 of the plant is recognized as one of 

 paramount importance. We know that 

 under certain conditions, if we give our 

 plants the proper food and the proper 

 cultivation, we may expect a reasonably 

 healthy crop. Neglect these factors and 

 we know that we may expect an un- 

 healthy crop. We know that soil, plant- 

 food culture and weather conditions all 

 have their influence on the health of 

 plants. 



We have come to learn, however, that 

 we cannot control many specific diseases 

 by cultural methods. We must resort 

 to spraying and seed or soil treatment 

 of various kinds. We know that we can 

 control apple, scab bitter rot of apples, 

 black rot of grape, and many other 

 similar diseases with Bordeaux Mixture. 

 We have come to realize that spraying 

 of certain crops is a necessity to success- 

 ful culture. The successful apple grower 

 sprays as faithfully as he prunes. The 

 successful potato grower, in sections 

 where late blight of potatoes is pre- 

 valent, sprays as regularly as he 

 cultivates, and is always assured of a 

 crop. The farmer who wishes a crop of 

 oats free from smut knows that he may 

 obtain such a crop by proper treatment 

 of seed before planting. The market 

 gardener who grows cabbage with the 



