. Circular. Agriculture -- Massachusetts. Circular No. 51. (Revision of No. 40.) March, 1915. MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION, AMHERST. DOWNY MILDEW OE CUCUMBERS. (Peronoplasmopara cubensis (B & C) CI.) By George E. Stone. Downy mildew, which is not difificult to distinguish from other leaf fungi, is most likely to occur on greenhouse cucumbers in August and September, and has never been observed by us in greenhouses in the winter. The fungus occurs on the under side of the leaf, causing whitish or yellowish angular spots (see Eig. i,) and these spots are more prominent on gr
. Circular. Agriculture -- Massachusetts. Circular No. 51. (Revision of No. 40.) March, 1915. MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION, AMHERST. DOWNY MILDEW OE CUCUMBERS. (Peronoplasmopara cubensis (B & C) CI.) By George E. Stone. Downy mildew, which is not difificult to distinguish from other leaf fungi, is most likely to occur on greenhouse cucumbers in August and September, and has never been observed by us in greenhouses in the winter. The fungus occurs on the under side of the leaf, causing whitish or yellowish angular spots (see Eig. i,) and these spots are more prominent on greenhouse than on field cucumbers. Ordinarily,. Fig. I. Showing characteristic spotting of cucumber leaf by downy mildew (Peronoplasmopara) an attack of this mildew lasts but a few weeks, and causes only an insignificant spotting of the leaf. Reproduction is by means of small spores, which retain their vitality longest in a moist atmosphere. Downy mildew was first observed on material received from Cuba in 1868, and was later noted in Wisconsin in 1882. In 1888 it was found on cucumber leaves obtained from Japan, and in 1889 it was found in New Jersey, causing injury under glass, at wliich time it was also common on field cucumbers. During the same year it was reported abundant in Florida and Texas. In 1890 it appeared in Massachusetts and again in 1892, when it was found on greenhouse and field crops. In New Jersey it was common in 1891, 1892 and 1893, and in Connecticut and New York about the same Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Massachusetts Agricultural Experiment Station; Massachusetts Agricultural Experiment Station. Special circular. Amherst
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