20 CROWN-GALL OF PLANTS. 



SOUTH AFRICA. 



According to Dr. Thomas F. Dreyer, of Cape Town (oral communi- 

 cation), crown-gall occurs in Cape Colony on pear trees both in the 

 nursery and in the orchard, and large swellings of some sort also occur 

 on the limbs of apple trees. 



According to I. B. Pole Evans, plant pathologist at Pretoria (oral 

 communication), galls of this general character are common in South 

 Africa on rose, peach, willow, etc., appearing on the parts above 

 ground, especially after hailstorms, which are of frequent occurrence. 



Since these paragraphs were written we have received from Charles 

 P. Lounsbury, Government entomologist for Cape Colony, an ac- 

 count of these galls (Agricultural Journal, April, 1910) entitled "Giant 

 twig-gall of willow, poplar, peach, apple, and other trees," in 

 which he states that the gall is most common on willow (Salix haby- 

 lonica). The poplar (Populus alba), peach, apple, apricot, pear, and 

 rose are said to be attacked also. The largest gall seen by Mr. Louns- 

 bury on the willow was 5 inches in length by 3.5 inches in diameter. 

 He says: "Much larger galls than this are said to occur, but ones under 

 3 inches in length are far more numerous." They are said to be very 

 abundant on the branches of the willow and to injure it seriously, 

 killing the branches beyond the gall. It has been suggested by some 

 that the galls begin in wounds made by hail, and by others that they 

 start from insect punctures. The disease occurs also in the Transvaal. 

 These galls have been investigated by various experts (Mally, Mac- 

 Owan, Pole Evans, Lounsbury), but no conclusion is reached as to 

 their cause, except that Mr. Lounsburj^ says that Mr. Pole Evans has 

 discovered that a very common knot "which occurs throughout the 

 land on quince trees" is "associated with a particular fungus." 



Willow galls received from Mr. Lounsbury are reported on later in 

 this bulletin (p. 94) . Mr. Lounsburj^'s figures strongly suggest crown- 

 gall, but in conclusion he says: "It seems improbable that it [the 

 American disease] is identical with the South African trouble under 

 discussion." 



We have, however, produced the disease on willow with a schizo- 

 mycete isolated and subcultured from one of his galls. 



EARLIER STUDIES IN THE DEPARTMENT OF AGRICULTURE. 



The senior writer's first acquaintance with this disease (as it 

 occurs on peach trees) was in 1892 (Journal of Mycology, vol. 7, 

 p. 378). This was the first work on the disease in the Department 

 of Agriculture. In 1893 he spent about six months on the crown- 

 gall of peach, making microscopical studies and cultures with mate- 

 rial received from various places in California, and also with some 



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