. Journal of Agricultural Research. the group slightly injured into twoclasses—very slightly injured and slightly injured. Each per cent in the former class was allowed one-halfpoint, while the latter class was allowed its former rating of one point (see i lage 432, paragraph 2). Sept. xs, 1923 Corticium vagum on the Pea and Bean 437 Under these severe conditions total destruction of the plumule resultedat temperatures of 15° and 18° C^ At 9°, while most of the seed germin-ated normally, only i plant out^a possible 29 escaped injury. At thehigher temperatures the severity of attack decreased m
. Journal of Agricultural Research. the group slightly injured into twoclasses—very slightly injured and slightly injured. Each per cent in the former class was allowed one-halfpoint, while the latter class was allowed its former rating of one point (see i lage 432, paragraph 2). Sept. xs, 1923 Corticium vagum on the Pea and Bean 437 Under these severe conditions total destruction of the plumule resultedat temperatures of 15° and 18° C^ At 9°, while most of the seed germin-ated normally, only i plant out^a possible 29 escaped injury. At thehigher temperatures the severity of attack decreased more rapidly thanat temperatures below those most favorable for tissue injury, nevertheless, was obtained at 28°. An interesting featureof the experiments appeared in the fact that damage to the primaryroots occurred at temperatures of from 15° to 21°, although no visiblelesions were found on the smaller fibrous roots of the plant. k/SOr V I- - - -4-^^2f:^*^^z%sf ^/^*5*z2sk5* ^//iP/^yVi9 /L£i:?/>-://vs. /2 /^ /3 2/ 24- ST ,30 Fig. 3.—Effect of soil temperature upon the severity of injury caused to the pea by Corticium vagum. DISCUSSION OF RESULTS OBTAINED WITH THE PEAResults obtained from the three experiments on the pea agree essentiallywith those obtained by Jones in showing that within the temperaturelimits employed (9° to 29° C.) neither the high nor the low^ temperatureentirely inhibited injury from Coriiciwrn vagum. However, in unsterilizedsoil, as in Experiments i and 2, the fungus is shown to be definitelylimited in its pathogenic power at both the high and low these two experiments severe damage to the young plants was con-fined largely to temperatures of from 15° to 24°, with an optimum ofapproximately 18° C. Such favorable conditions for the pathogenicityof the fungus produced by sterilized soil, on the other hand, result in amuch wider temperature range for the vigorous action of tlie fungus,although even under th
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