Title:

Diseases and Insects in Dryland and Irrigated Cropping Systems Without Grass Burning

Objectives:

1. Continue to evaluate the effect of thermal and non-thermal residue management systems to control ergot, silver top, and rust.
2. Evaluate the effect of long-term bluegrass residue management rotations on the development of Rhizoctonia footrot in cereals.
3. Evaluate available bluegrass cultivars for ergot resistance.
4. Continue to evaluate ergot control with fungicides and surfactants.
5. Identify insect species active during flowering of Kentucky bluegrass and carrying conidia of C. purpurea.

Principal Investigators:

W. J. Johnston, Assistant Agronomist
Dep. Crop and Soil Sciences, WSU
J. W. Sitton, Plant Pathologist, Post Doctoral Research Assoc.
Dep. Crop and Soil Sciences, WSU
M. D. Butler, Extension Crop Scientist, Central Oregon Agric. Res. Ctr.
Dep. Crop and Soil Science, OSU

Cooperators:

R. J. Cook, Research Plant Pathologist
USDA-ARS, WSU, Pullman
R. F. Line, Research Plant Pathologist
USDA-ARS, WSU, Pullman
G. Murray, Professor, P.S.E.S.
University of Idaho, Moscow
G. Fisher, Extension Entomology Specialist
Department of Entomology, OSU
S. C. Alderman, Research Plant Pathologist
USDA-ARS National Forage Seed Production Research Center
R. Johnson, Research Agronomist, USDA-ARS
Western Regional Plant Introduction Station, Pullman
B. Cagas, Agronomist, Grassland Research Station
Zubri, Czech Republic
P. Peterson, WSU, Cooperative Extension
Spokane County, WA
P. M. Gray, Research Technologist, Department of Plant Pathology
WSU, Pullman

Abstract:

In 1996, a severe ergot year, residue removal techniques did not reduce the severity of ergot. Residue removal with crew cutting, but not rotary raking or minimum removal (bale only), reduced the severity of silver top. Rust was not reduced by any treatment compared to open-field burning. Data indicates a possible association of an insect and Fusarium poae as causal agent in silver top disease. Use of surfactants, without fungicides, reduced ergot in Post Falls, ID test plots. Rhizoctonia and Pythium were shown by J. R. Cook et al. to have a detrimental effect on cereal crops following non-burned bluegrass in rotation. Bluegrass germplasm and commercial cultivars were evaluated for ergot resistance, but results were inconclusive in 1996. Bluegrass germplasm was exchanged with the Czech Republic and ergot evaluation plots were established in 1996. These plots will be innoculated with C. purpurea, fall 1996. This study is the first comprehensive survey of insects associated with Kentucky bluegrass seed produciton and established a baseline for furture studies, both locally and regionally. Fields sampled contained predatory damsel bugs, flies, leafhoppers, predaceous lady bird beetles, lygus bugs, and big-eyed bugs.

Justification:

The grass seed industry has used open-field burning as a simple, inexpensive and effective means to control a broad spectrum of grass diseases. Investigators differ in their assessment of which diseases are most serious in the Pacific Northwest. A disease assessment is "key" to developing control options in absence of open-field burning. Once the important organisms have been identified, disease control options will be investigated.

An understanding of the ecological associations of C. purpurea and insects, and their interactive dynamics is essential to development and evaluation of control strategies for ergot. This is especially true in development of cropping systems where field ecological relationships may vary among production systems. Results of this study may be useful in understanding host insect interaction or other disease vector relationships. In addition, understanding the ergot insect relationship is prerequisite to development of any predictive model for ergot.