Distribution and ethological role of strands of Phymatotrichum omnivorm (Shear) dug.
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Abstract:
Viable strand lengths (VSL) of Phymatdtrichum dmriivdrum (per 50 g soil) of 0,1 and 0*2 cm were recovered at 15-30 and 30-60 cm depths 9 respectively9 in cotton fields near Marana? Arizona in June, 1979; none were recovered at depths of 0-15 and 60-90 cm. Maximum VSL occurred from August into November„ These were 0.5, '0.4, 1.0, and 0.6 cm at depths of 0-15, 15-30, 30-60, and 60-90 cm, respective ly. By April, 1980, VSL at the same depths were 0,05 9 0.2, 0.3, and 0.05 cm, respectively. All infected cotton roots from depths of 1545 cm in August contained viable strands, generally fewer roots con tained viable strands in other months and at 0-15 cm depths. Phymatotrichum omnivorum was isolated from tissues of infected cotton roots in August but not from rotted roots after October. Inoculations of cotton plants with strands were unsuccessful. However, 46% of the plants became diseased when naturally infected roots were used as inoculum in the field and 50%-100% were infected : : ' • • when sclerotia or infected sorghum seeds were used as inoculum in the . i greenhouse. Sclerotia from field or laboratory cultures germinated M only from attached broken strands. / ?Cite