ABSTEACTS: PHYTOPATHOLOGY 13 



the area of complete infection from the comparatively uninfected area 

 by an immune zone. Advance infections should be located by trained 

 observers and destroyed by cutting and burning. As the disease de- 

 velops almost entirely in the bark, this must be completely destroyed 

 (burned). 



In order to carry out the above methods it is essential that the several 

 States concerned secure necessary legislation and appropriations, follow- 

 ing the example of Pennsylvania, as no law exists whereby the federal 

 government can undertake such work and cooperation among private 

 owners without State supervision is impracticable. 



Chestnut nursery stock should be rigidly inspected for the disease and 

 only perfectly healthy plants passed. 



The life of valuable ornamental trees may be greatly prolonged by 

 promptly cutting out all diseased areas and removing all disease-girdled 

 branches and then covering the cuts with tar. Spraying is of no use 

 in stopping the fungus after it has once started growth in the bark. 



It is recommended that owners of infected woodland cut down and 

 utilize the diseased chestnut timber as soon as possible. 



For the present the planting of chestnuts anywhere east of Ohio is 

 not advised, but there is no apparent reason why chestnut orchards west 

 of Ohio may not be kept free from the disease. H. M 



PHYTOPATHOLOGY.— Root knot and its control. Ernst A. Bessey, 

 Bureau of Plant Industry. Bulletin No. 217, pp. 89, 3 pi., 3 figs. 

 1911. 

 The disease known as root knot is abundant in sandy soils thruout 

 the warmer parts of the United States and more sporadically in other 

 regions. It is due to the attack of a nematode, Heterodera radicicola 

 (Greef ) Miiller, a near relative of the European sugar beet nematode, H. 

 schachtii. The disease was first recognized in Europe in 1855. Its 

 first mention in print in this country seems to be in the latter part of the 

 eighties altho it had been observed by florists in greenhouses as early 

 as 1876. It has been found to be present in North and South America, 

 West Indies, Europe, Asia, Africa, East Indies, Australia and Hawaiian 

 Islands. It seems to be tropical in its origin, probably having been na- 

 tive to the Old World. A list of plants susceptible to root knot is given, 

 including 480 species, on 291 of which the author observed the parasite 

 himself, the highest previous list including only 235 host plants. The 

 plants included represent almost all of the more important families 

 of dicotyledons and monocotyledons as well as one gymnosperm and one 



