. Bulletin. Agriculture -- Ontario. 21 (Fungi).. Downy Mildew (Peronospora schleidenii) : This is a common dis- ease of onions. The leaf first shows yellow patches, covered with a greyish mould. Later, the patches increase in size and numbers, and the leaf shrivels and dies. Two kinds of spores are produced, viz., thin- walled summer spores, on the minute branched stalks forming the greyish mould, and thick-walled winter spores (oospores), in the tissues of the leaves killed by the fungus. The summer spores are scattered by the wind during summer, and are the agents in the spread of the diseas
. Bulletin. Agriculture -- Ontario. 21 (Fungi).. Downy Mildew (Peronospora schleidenii) : This is a common dis- ease of onions. The leaf first shows yellow patches, covered with a greyish mould. Later, the patches increase in size and numbers, and the leaf shrivels and dies. Two kinds of spores are produced, viz., thin- walled summer spores, on the minute branched stalks forming the greyish mould, and thick-walled winter spores (oospores), in the tissues of the leaves killed by the fungus. The summer spores are scattered by the wind during summer, and are the agents in the spread of the disease. Treatment: Rotation of crops is necessary, especially when winter spores are in the infected soil; removal and burning of diseased plants; spray with Bordeaux or potassium sulphide (i ounce to 2 gallons of water); dusting the plants with powdered quicklime and sulphur (2 to 1).. Tkuk Squash Bug. (Anasa tristis, De G.). a. mature female; b. side view of head, showing beak ; c. abdominal segments of male ; d. same of female ;—a. twice natural size ; b., <:, d., slightly more enlarged. After Chittenden, Div. of Entomology, Dep. of Agriculture. Smut (Urocystis Cepulce) : This disease is often troublesome to con- trol. Early in the season leaves of onions may show the black smut masses arranged more or less in lines. The onions are only infected dur- ing their seeding stage from the spores, either attached to the seed or lying in the soil, hence the danger of planting onions in smut-infested soil. Treatment: Destroy and burn diseased plants; when soil is smut- infested grow seedlings in smut-free soil, then transplant; in infested soil "apply in the drills, per acre, one hundred pounds of sulphur thoroughly mixed with fifty pounds of air-slaked lime; sprinkle seed with formalin solution (1 pound to 30 gallons of water) to kill the attached ; Black Mould (Macrosporium parasiticum) : This fungus is usually found associated with the Downy Mildew, but it is supp
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