. Diseases of field crops in the Prairie Provinces. Plants; Cultures de plein champ; Cultures de plein champ; Plantes. FLAX break over at the weakened first node (Fig. 20). They may live after falling over, but even if seed is set, it is usually lost in harvesting. Infections on the upper part of the stem appear as oval or elongate brown spots, about one-quarter inch long. The spots, which usually remain separate, are often surrounded by a narrow, purplish margin. Sometimes the spots are numerous enough to grow together and cover much of the stem. Patches of heavily infected plants appear brow
. Diseases of field crops in the Prairie Provinces. Plants; Cultures de plein champ; Cultures de plein champ; Plantes. FLAX break over at the weakened first node (Fig. 20). They may live after falling over, but even if seed is set, it is usually lost in harvesting. Infections on the upper part of the stem appear as oval or elongate brown spots, about one-quarter inch long. The spots, which usually remain separate, are often surrounded by a narrow, purplish margin. Sometimes the spots are numerous enough to grow together and cover much of the stem. Patches of heavily infected plants appear brown, giving the disease the name 'browning'. The fungus may attack the bolls and penetrate into the seeds. If the seeds are infected while they are young, they may be killed. If they are attacked when they are relatively mature, the fungus grows into the seed coat and survives Figure 20.—Stem break of flax. The horizontal line represents the soil line. (Photograph by courtesy of Prof. T. C. Vanterpool.) Disease Cycle—When diseased seed is sown and germinates, the seed-coats are carried above the soil by the seed leaves and spores from the seed coats start infections in the new crop. The fungus can also survive the winter on diseased stubble and produce spores, which may be spread by wind and rain. 71. 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 Canada. Agriculture, Department of; Canada. Dept. of Agriculture. Ottawa [Queen's Printer]
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