1909.] American Gooseberry Mildew. 



119 



the resting spores early in May, but that the majority burst in 

 June or July. Some winter fruits remain attached to the 

 infected twigs throughout the winter, but the greater number 

 fall off and lie in the soil. 



Conditions under which Disease Occurs. — American 

 Gooseberry Mildew attacks soft quick-growing shoots; thus 

 suckers, and the shoots produced in warm, moist weather, 

 are much more liable to infection than firm, slow-growing 

 shoots. This explains a feature of the disease which often 

 puzzles growers. When a new district is attacked, the first 

 plantations to suffer are those which have been highly 

 manured and carefully managed. The large, quick-growing 

 bushes produced by such treatment are found to be much 

 more liable to attack than the poor plants in a neglected 

 garden. 



Some varieties of gooseberry are naturally more vigorous 

 than others, and thus produce more young wood in the late 

 summer and autumn ; these varieties are found to be most 

 affected by mildew. For example, the quick-growing varie- 

 ties "Keepsake," "White Lion," and "Crown Bob " con- 

 tract disease to a greater extent than the slow-growing 

 varieties "Whitesmith," "Careless," and " Long Swan." 

 Apart from the rate of growth and the nature of the new 

 shoots produced, varieties do not seem to have any special 

 capacity for resisting disease. Thus " Golden Drop " is not 

 so liable to attacks on the young wood as most other varieties, 

 but the berries, which happen to have a soft skin, are more 

 apt to suffer from mildew than those of any other kind. In 

 most varieties disease does not appear to be able to attack 

 the berries after they are half-grown, but in " Golden Drop " 

 full-grown berries may suffer. 



Deep, porous soils produce tall, vigorous plants, while 

 shallow or stiff soils produce small bushes, so that disease is 

 more troublesome on the former than on the latter class of 

 soil. When, associated with deep, porous soils, there is an 

 abundance of moisture, as in the silty soils of the Wisbech 

 district, the conditions are specially favourable for the spread 

 of mildew. In gardens in all affected districts variations in 

 the depth of the soil, and in the amount of moisture, account 

 for the unequal distribution of disease throughout infected 

 plantations. 



