EXPERIMENT STATION BULLETINS. 277 



WHITE HELLEBORE. 



This is a mild vegetable poison which is sometimes used in the place of 

 the arsenites. It may be used either in the powder, by dusting over the 

 plants, or liquid form, at the rate of a heaping tablespoonful to two gallons 

 of water, and applied as a spray. 



TOBACCO DECOCTION. 



For some insects a tea made of tobacco, or refuse stems, at the rate of 

 one pound to five or six gallons of water, is highly recommended. Boiling 

 water may be turned over the tobacco, or, better, let it steep a short time 

 and strain when cool. 



HOT WATER. 



This is a remedy which is simplicity itself and needs no explanation for 

 preparation except that most insects are killed by it at a temperature of 

 130 to 140 degrees. The foliage of some plants will not endure heat 

 much greater than this, while such plants as the cabbage will endure water 

 raised to 180 degrees without injury. Where insects are working near the 

 surface of the ground, as root lice, or at the base of the trunk, as the peach 

 tree borer, water is often used boiling hot with telling effect on the insect 

 without injury to the tree. 



THE DISEASES OF PLANTS. 



A plant may be considered in a diseased condition when any of its organs 

 are unable to properly perform their normal functions. This may be 

 brought about by a great variety of causes, many of which are beyond our 

 control, such as extremes of temperature, an excess or a deficiency of moist- 

 ure, an improper supply of food, either in kind or amount, or, as perhaps 

 is most common, by the work of either insects, fungi, or bacteria. 



Much can be done by the grower to give the plants a suitable location, 

 soil, and food, and this will do much to keep the plants in health, but the 

 influences that affect the nutrition of the plants are by no means all of 

 them under control, and the conditions that in one season may give good 

 results may not be present in another. 



While plants that are growing in congenial surroundings are less subject 

 to the attack of parasitic fungi than those that are suffering for lack of 

 them, those that are apparently in the best condition to withstand the 

 attack of these parasites do not always escape. It is true, however, that if 

 they are abundantly supplied with food they will suffer less from the attack 

 of the fungus than if the food supply is short. 



So far as is now known, most of the parasites that prey upon plants are 

 of a fungous nature. Fungi are a low order of vegetable life and most of 

 them obtain their sustenance fiom other plants or animals. In case their 

 hosts are living they are said to be parasites, but if the food comes from 

 decaying organic matter the name saprophyte is applied to them. The 

 former are the ones that cause disease in plants, although the saprophytes 

 may appear in living plants, feeding on the tissues that have been destroyed 

 by the parasitic fungi or in any other way. 



