Diseases of economic plants (1921) Diseases of economic plants diseasesofeconom01stev Year: 1921 410 Diseases of Economic Plants In the seed bed the same disease may occur as damping- off. See p. 19. It seems that original infection always oc- curs in the seed bed, never in the open. Plants started in the open are not susceptible. If it is necessary to start them under glass, too thick sowing should be avoided, and they should be ventilated thoroughly. Soil that is known to be in- fested should not be used. The disease may be pre- vented by avoidance of the conditions that favor damp- ing-of
Diseases of economic plants (1921) Diseases of economic plants diseasesofeconom01stev Year: 1921 410 Diseases of Economic Plants In the seed bed the same disease may occur as damping- off. See p. 19. It seems that original infection always oc- curs in the seed bed, never in the open. Plants started in the open are not susceptible. If it is necessary to start them under glass, too thick sowing should be avoided, and they should be ventilated thoroughly. Soil that is known to be in- fested should not be used. The disease may be pre- vented by avoidance of the conditions that favor damp- ing-off. Yellows. - — Growth is spindling and the shoots and leaves are yellow, but no death of affected parts occurs. In badly diseased plants no flowers, or only rudiments of such, develop upon the sick shoots. In other cases the flowers turn greenish-yellow, wholly or in part, with malformed floral parts producing little or no seed. No parasites are present and the cause of the condition is unknown, but the striking similarity to peach yellows is obvious. The same disease affects the marguerite. Rust {Coleosporium solidaginis (Schw.) Thuem.). — Orange-red sori, waxy in consistency, are produced in great numbers upon the leaves, which when badly affected curl, die, and thus bring about the death of the plant. Stem- rot {Corticium). — See p. 21. Fig. 216. — Rust on barberry. After Stakman.
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