DISEASES OF PLANTS. 363 



length and are 1-celled, while the most are 30 to 50 pi and 2 or 3 

 celled, while occasionally specimens are found 100 n in length and 

 have 8 to 10 cells. The conidia are able to produce spots on sound 

 leaves in from 4 to 5 days ; when severely attacked the leaves quickly 

 dry up and fall from the plant. 



The disease of the peanut is said to be due to an undescribed fun- 

 gus (Septoglceum araehidis) and whole fields are said to have been 

 destroyed by it. It produces round, sharply bordered black spots 

 with lighter centers and a clear yellow limiting border. The spots are 

 usually 4 to 5 mm. in diameter, but vary from 3 to 10 mm. While 

 usually found on the lamina and midrib of the leaf, the petioles and 

 stems are also attacked. Infected leaves quickly fall, leaving the 

 bare stems and a few young leaves. The mycelium of this fungus 

 occurs in the parenchyma and sends numerous haustoria into the cells. 

 The conidiophores are small and they bear numerous elliptical conidia, 

 usually single-celled, but sometimes appearing as though 3 to 5 celled. 

 They are 20 to 31 ji in length and 9 // in diameter. By placing fresh 

 conidia on leaves the characteristic spots are said to have been 

 produced within four days. 



A dangerous disease of the white pine ( Gard. Ghron., 3. ser., 23 

 (1898), No. 588, p. 202). — The author calls attention to the serious dis- 

 ease of Finns strobus due to Peridervnium strobi. The disease is widely 

 distributed in Germany, Denmark, and elsewhere, and is quite com- 

 mon in the nursery. The symptoms of the disease consist of a swelling 

 on twigs or branches, frequently under a branch whorl. Soon the dis- 

 tinctive blister-like outgrowths appear, bearing the yellowish spores. 

 In a short time the twigs dry up, the needles fall, and no new growth 

 follows. 



The alternate generation of this fungus occurs on the black currant, 

 gooseberry, and other species of liibes. This form is known as Gronar- 

 tium ribicolum, and it appears on the leaves in June as a yellow, rusty 

 coating, followed by a number of brown hair like outgrowths. On the 

 currants, etc., while destructive, it has not been reported as epidemic. 

 Pinus strobus in America is said not to be attacked by this fungus. 



Experiments for the control of potato scab, II. Garman ( Ken- 

 tucky 8ta. Bui. 72, pp. 9-23). — In 1896 the author conducted a series of 

 experiments with corrosive sublimate and flowers of sulphur for the 

 prevention of potato scab. The first series was conducted in the 

 greenhouse. A scabby potato was planted in each of 6 10 in. flower 

 pots, the soil in all having been previously baked for several hours. 

 The results obtained by this somewhat limited experiment indicated 

 that sulphur did not exercise any decided effect in checking the scab, 

 while corrosive sublimate proved very efficient. 



Later in the same season 10 tenth-acre plats which had been previously 

 used in potato-scab experiments (the ground being infested with a 

 potato-scab fungus) were planted with Early Kose potatoes, the object 



