EXPERIMENT STATION REPORTS. 311 



GRAPE DISEASES. 



Grape Black Kot appeared as an epidemic in Michigan vineyards last 

 season. Here there seemed to be a contradiction to the common belief 

 that the Black Kot is synchronous with a wet season. At Lawton and 

 Paw Paw in spite of a drought condition the grapes rotted so badly that 

 there was onl}- half a crop. The matter is clearly explicable if it be re- 

 membered that the virulence of early infection controls the later out- 

 breaks. Infection of grapes occurred in May and June on account of 

 the excessive rainfall. Spraying applied, as per rule, could not be 

 timely. As a result, abundant leaf infection and abundant infection of 

 berries shortly after the blossoming occurred. In the early half of Aug- 

 ust the bunches showed great promise, aside from the fact that small 

 black rotted berries persisted from the early infections. A heavy rain 

 about July 26th and another about three weeks later caused the loss of 

 the crop. A few growers whose sprayings were timely so as to give pro 

 tection at the first rainy period had a good crop. In general the croj) 

 was a disappointment. Vineyards in good sanitary condition showed 

 less rot than neglected ones. 



Sun scorch of leaves and fruits occurred last year. These troubles all 

 show the general characters of this type of disorder, yellowed leaves 

 with brown, parched edges, but are hard to diagnose and erratic in oc- 

 currence. 



Lightning injury was reported by one grower as a common occurrence 

 in grape vinej'ards. Lightning striking a wire will kill grape vines along 

 the wire for several rods. The electrocuted vines wither slowly and pre- 

 sent a confusing train of symptoms. 



ROOT ROT OP STRAWBERRIES. 



Strawberry plantings last year showed almost a complete failure in 

 many fields. Keports of trouble were received from at least six counties. 

 The plantings made at the College with first-rate plants failed to give a 

 good stand. 



The cause of this is hard to explain. It is certainly associated with 

 the wet season at planting time. The roots of the plants failed to start 

 and merely rotted. Microscopic examination showed Rhizoctonia on the 

 roots. It is believed, however, that the soggj^ soil conditions lead to the 

 rotting of roots rather than that a new active parasite had developed. 



PEACH DISEASES. 



Powdery Mildew is a disease common but not usually reported as se- 

 vere. It was sent in by a correspondent from Oceana County. It was 

 reported as causing injury to the crop. 



Because of the cold wet April, Leaf Curl defoliated many orchards 

 in Michigan last year and caused much loss to the growers. In spite of 

 the well known control measures, the necessary spray is neglected by 

 many fruit growers. 



Cercospora circumscissa was very common last year. Peach leaves 

 have been received from many localities showing the characteristic red 

 spots of this disease. An orchard near South Haven showed the disea.se 

 so severe that the trees were nearly defoliated at jjickiiig time. While 

 the loss is difficult to estimate the wasting nature of this disease is ap- 

 parent. Summer sprays are peculiarly effective in control of this trouble. 



