312 STATE BOARD OF AGRICULTURE. 



RASPBERRY CURL OR YELLOWS. 



Eed raspberries affected Avitli Curl or Yellows have been sent from sev- 

 eral localities in the i)ast few years. Affected plants show curled, dis- 

 torted leaves with prominent grooves at the leaf veins. The fruit from 

 diseased plants is scanty and poor in quality. Commonly only a few 

 carpels develop fully. This disease is potentially a serious one and in- 

 stances are reported where entire plantings have been ruined. 



POTATO DISEASES. 



The common potato diseases previously known for the state were 

 found in their usual prevalence. Potato Scab was seen everywhere as 

 well as a type of trouble caused by Rhizoctonia which is commonly con- 

 fused with Scab. In the later type of trouble no corking of the skin de- 

 velops, the scabbiness showing as a black scurfy patch, commonly 

 marked or colored with cross lines. This developed on the cro]) groAvn 

 from treated seed on soil which had not borne potatoes previously. The 

 evidence seems to point to the existence of Rhizoctonia as a common soil 

 denizen and that the virulence of the soil form is less than that carried 

 on the tubers. Under peculiar soil conditions the ordinary soil forms 

 take on some pathogenicity. 



Late blight was not found at all as would be expected from what we 

 know of the relation of this parasite to a cold, wet July. The drought 

 was effective in preventing the appearance of the parasite in any notice- 

 able degree. It must not be expected, however, that the disease has been 

 Avholly eliminated from our seed stock, for undoubtedly enough leaves 

 have become affected and a few tubers have slight spots, readily over- 

 looked, to insure the development of the fungus in another season if the 

 weather in the first half of the growing season is propitious. 



Fusarium Wilt was found everywhere stunting the plants and lead- 

 ing to marked yellowing and wilting of the tops. It would seem that the 

 extra demand for water under the drought conditions in addition to the 

 systemic poisoning which occurs in this disease was responsible for the 

 development of this symptom. 



Early Blight developed in the northern part of the State but was 

 largely absent in' the southern half of the State. The weather in the 

 north was hot but the rainfall was moderate. In the southern portion 

 the extreme dry weather led to tip burn with little or no development of 

 early blight. This adjustment to weather has largely been borne out in 

 previous years' experience in this state and we look at Late Blight as a 

 disease which appears when the first half of the season is cold and wet. 

 Early Blight when the season is moderately wet — its effects in wet sea- 

 sons being obscured by Late Blight — and Tip Burn when the season is 

 dry and the fields parch. 



Black Leg was found commonly in the Upper Peninsula but was not 

 reported from the Lower Peninsula, although the weather of May and 

 June Avould have insured its development, had the disease been present 

 in the tubers. Up to date, only one case of Black Leg has been reported 

 for the southern counties of Michigan and this one in stock im])orted 

 from the north. It is not known whether this disease is climate limited 

 or has merely not been introduced. 



Streak, a disease new to Michigan was discovered in fields near Che- 

 boygan, Michigan, by Dr. Edson of the U. S. Department of Agriculture. 



