Identification

Author

DeVay JE, Garber RH, Matheron D

Title

Role of Pythium species in the Seedling Disease Complex of Cotton in California

Year

1962

Publication type

Article

Journal

Plant Disease

Created

2015-07-31 14:33:02.026853+00:00

Modified

2016-07-29 21:36:24.665728+00:00

Details

Volume

66

Access

Language

English

URL http://www.apsnet.org/publications/plantdisease/backissues/Documents/1982Articles/PlantDisease66n02_151.pdf
DOI

10.1094/PD-66-151.

Accessed

2016-07-13

Extended information

Abstract

Survival of cotton seedlings (Gossypium hirsutum, cv. Acala SJ-2) grown from acid-delinted seed in six field tests during 1976 in the San Joaquin Valley of California was directly related to the concentration of soilborne propagules of Pythium ultimum. The viable propagules of P. ultimum recovered from soil were mainly oospores, but sporangia were occasionally found. Plant residues were the second most frequent source of viable propagules. Seedling survival ranged from 90 to 22% at 0 and 217 propagules of P. ultimum per gram of soil, respectively, with the death of 50% of the seedlings at approximately 100 propagules per gram of soil. Pythium species other than P. ultimum were present but at relatively low concentrations in soil samples. Pathogenicity tests indicated that P. ultimum and P. aphanidermatum were the most virulent species on cotton seedlings. Assays of Pythium species in samples of naturally infested field soils that were air-dried and stored at 23 C or kept moist and stored in sealed polyethylene bags at 4 or 23 C indicated that neither the period of storage (up to 5 mo) nor the conditions of storage caused any significant changes in populations of Pythium species.