Indiana Plant Diseases, 1921 187 



of loss in the late crop and resulted in very poor stands in central In- 

 diana. Certain fields were almost a total loss because of this trouble. 

 According to Gaylord's observations, this failure occurred mainly in 

 potatoes planted about the middle of June and is attributed by him to 

 high soil temperature. He found that the loss in stand was very much 

 less in the fields which were rolled after the seed was planted. 



Quince. — H'^avy spotting of the fruit due to Fahraea macnlata was 

 noted in Lafayette. 



Radish. — Black-root, caused by RJieosporangium aphanidermatum, 

 was a very serious trouble in the icicle varieties in the early market 

 garden crops. It was noted near Indianapolis in April and May and 

 was prevalent in gardens in Lafayette in May. It is not a factor in 

 the midsummer crop, but may occur in the fall. In a variety test sown 

 by Brown on August 20, the disease occurred in the fall on the varieties 

 Early Long Scarlet, Early Vienna and Cincinnati Market. By the 

 agar plate method a fungus resembling R. aphamdermatum was isolated 

 from diseased roots. 



Downy mildew {Peronospora parasitica) was found doing consider- 

 able damage in beds of small red radishes in an Indianapolis market 

 garden on April 27. The leaves were thickly spotted with small, irregu- 

 larly lobed, sharply defined, black lesions (fig. 9A) bearing sporophores 

 of the fungus on the lower side. On the upper portions of many of the 

 roots were small, sunken, black lesions caused by the same fungus (fig. 

 9E). Under these root lesions there was in some cases some blackening 

 of the tissue indicating that the fungus had penetrated to a considerable 

 extent. Under damp chamber conditions in the refrigerator, sporulation 

 of Peronospora occurred on these surface root lesions and on the cut 

 surfaces of the blackened root tissue. Microscopic examination showed 

 abundant haustoria within the host cells. The occurrence of Peronospora 

 in turnip roots has been previously recorded (15). The occurrence of 

 Peronospora in red radish roots was noted by a German observer (4) 

 in 1899, however, and in black or summer radishes by another (40) in 

 1908. On May 25, leaf lesions similar to those described above were 

 noted on older plants on another farm and blackened petiole and stem 

 lesions were also noted. There was extensive blackening of the pith 

 of these seed stems (fig. 9C) due to Peronospora infection. In another 

 field, more recent foliage infection on icicle and white globe radishes 

 was abundant, but in this case the lesions were the typical angular, 

 intervenous areas (fig. 9B), yellowish above and covered with a white 

 velvety mass of sporophores below. 



White rust (Cyst opus candidus) occurred in the greenhouse crop 

 near Lafayette in the early spring and was found abundant in the 

 Indianapolis market gardens in May. It w<as noted in abundance on 

 a row of seed radishes in a Lafayette market garden on June 28. 

 Radish seed pods infected with both downy mildew (fig. 9D) and white 

 rust were collected in 1920 (17, p. 201) and a considerable quantity 

 of seed from these pods was planted in the greenhouse but no evidence 

 of seed transmissicn of either of these diseases was obtained. 



Raspberry. — /pthracnose, caused by Plectodiscella veyieta, remains 

 the worst disease of the black raspberry in Indiana. It was reported 



