Diseases of truck crops Diseases of truck crops / Ralph E. Smith diseasesoftruckc119smit Year: 1940 40 California Agricultural Extension Service [CiR. 119 can be controlled by dusting or spraying with nicotine (Black Leaf 40). (See Extension Circular 87.) Cauliflower Mosaic.—The leaves of mosaic plants are mottled, dis- torted, and frequently covered by small, dead areas (fig. 20). Plants are stunted and seldom produce heads of marketable size unless infection Fig. 21.—Club root on turnip. occurs very late. All commercial varieties of cauliflower grown in Cali- fornia are susceptible. Ca
Diseases of truck crops Diseases of truck crops / Ralph E. Smith diseasesoftruckc119smit Year: 1940 40 California Agricultural Extension Service [CiR. 119 can be controlled by dusting or spraying with nicotine (Black Leaf 40). (See Extension Circular 87.) Cauliflower Mosaic.—The leaves of mosaic plants are mottled, dis- torted, and frequently covered by small, dead areas (fig. 20). Plants are stunted and seldom produce heads of marketable size unless infection Fig. 21.—Club root on turnip. occurs very late. All commercial varieties of cauliflower grown in Cali- fornia are susceptible. Cabbage and peach aphids, which breed naturally on this host, readily transmit the causal virus to healthy plants after feeding on diseased leaves. Losses could be materially reduced by dusting or spraying with nico- tine for aphid control while the plants are young, with applications at 10-day intervals (see Extension Circular 87). Plants showing visible symptoms (fig. 20, top) should not be put out in the field. Club Root.—This is another important fungus disease which, for some unknown reason, is extremely rare in California. It is caused by Plas- modiophora hrassicae. Affected plants are yellow and sickly and wilt
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