. Bulletin. Natural history; Natural history. Diseases of Grain Croi's. 1922-1926 67 Oats Halo Blight Caused by Psciidoiuoiias coronafiicicns ( Elliott) Stev. Though the syniptonis presented by the halo blight of oats are quite (litTerent from those shown by the leaf spot of wheat discussed above, the method of estimating its destructiveness is much the same. Its preva- lence is determined, of course, as the percentage ratio of disease-bearing stalks. For estimating the intensity of the attack, a special scale, shown with considerable reduction in Figure SO, has been devised. The eftect produc
. Bulletin. Natural history; Natural history. Diseases of Grain Croi's. 1922-1926 67 Oats Halo Blight Caused by Psciidoiuoiias coronafiicicns ( Elliott) Stev. Though the syniptonis presented by the halo blight of oats are quite (litTerent from those shown by the leaf spot of wheat discussed above, the method of estimating its destructiveness is much the same. Its preva- lence is determined, of course, as the percentage ratio of disease-bearing stalks. For estimating the intensity of the attack, a special scale, shown with considerable reduction in Figure SO, has been devised. The eftect produced by halo blight in destroying leaf tissue appears to be consider- ably less than the similar elTect of the wheat leaf spot. The degrees of destructiveness are more readily distingnishalile. which ijerniits the use. Pig. 80. Standard for .mi:asi:ring the destructiveness of oats blight The black spots on each diagrammatic leaf represent the tissue killed by the halo blight bacterium. The area of the spots has been measured and is given as a percentage of the entire leaf area for each diagram. Random sam- ples taken in each field are compared with this scale, and the destructiveness of the disease is computed in terms of leaf area destroyed (see page 69). of a larger number of individual standards in the scale and results in a consideiably greater degree of accuracy in the estimates. Otherwise, the methods of obtaining field data are the same as those previously discussed. During l'J22, with halo blight of oats as with several other cereal diseases, data were recorded exclusively in the northern half of the State. Definite records were taken in â ") fields which contained a total of ilT acres and were located in the 4 counties shown in Figure 81. Al- though their combined acreage is not impressively large, their wide. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance
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