| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00649 | |
| Title | *Occurrence, Distribution, and Control of Wheat Streak Mosaic Virus and High Plains Virus Diseases of Winter Wheat in Colorado |
| Investigator(s) | Hill, JP |
| Department | Bioagricultural Sciences and Pest Mgmt. |
| Objectives | Determine the distribution of Wheat Streak Mosaic Virus and High Plains Virus in Colorado. Determine the pathogenic variation in the Wheat Streak Mosaic Virus population in Colorado, Nebraska, and Kansas. Evaluate Colorado winter wheat culitvars and germplasm for resistance to Wheat Streak Mosaic Virus. Develop a quantitative method of identifying resistance to Wheat Streak Mosaic Virus in wheat seedlings that correlates to field reaction and yield. Incorporate resistance to Wheat Streak Mosaic Virus into the major Colrado wheat cultivars. |
| Approach | A survey of winter wheat and corn throughout at least two growing seasons will be conducted by collecting plants with mosaic symptoms. The plants will be tested for presence of Wheat Streak Mosaic Virus (WSMV) and High Plains Virus using specific antiserum. A population of WSMV isolates will be prepared by inoculating a susceptible wheat cultivar with extract from leaves expressing mosaic symptoms. The WSMV population will be assessed on a series of differential winter wheat culitvars. Germplasm will be evaluated for resistance using a quantitative seedling root reduction method utilizing digital imaging and color analysis. Mosaic response will be measured with a chlorophyll meter. Resistant germplasm will be utilized in the wheat breeding program to develop culitvars resistant to WSMV. |
| Keywords | wheat streak mosaic virus, high plains disease virus, disease resistance, winter wheat breeding, evaluation of germplasm, variation in virulence |
| Progress Reports | |
| 2000 | An increase in foliar mosaic virus disease of winter wheat has been observed during the last several years in the high plains of Colorado. Wheat Streak Mosaic Virus and High Plains Disease Virus have been associated with this increase in disease incidence. A survey was initiated to determine the extent of the disease caused by each virus. The 2000 winter wheat crop was surveyed in the high plains of Colorado during late spring and early summer for plants exhibiting foliar virus disease symptoms. The extended drought and high temperatures during the growing season supressed the occurrence and dissemination of the pathogens and made it difficult to find and identify diseased plants. Wheat Streak Mosaic Virus was isolated from 18 diseased plants exhibiting foliar symptoms to the virus disease. The survey will extend through the current growing season. No High Plains Disease Virus was identified from any of the diseased plants. The Wheat Streak Mosaic Virus isolates are being evaluated for pathogenic variation within and among several winter wheat cultivars. |
| 2001 | The Wheat Streak Mosaic (WSMV) and High Plains Disease Virus (HPDV) survey in eastern Colorado was continued. Winter wheat plants exhibiting foliar mosaic symptoms were collected and tested for presence of the two viruses using ELISA test kits. No high levels of plants exhibiting mosaic sympotoms were found in the field this year. Less than half the plants tested positive for WSMV and none were positive for HPDV. Plants will be tested for the presence of three strains of Barley Yellow Dwarf Virus (BYDV). Winter wheat seedlings were randomly collected from five fields planted adjacent to dryland corn. Samples were obtained along four parallel lines approximately 5, 30, 60, and 100 feet from the corn fields. The winter wheat plants exhibited no foliar symtoms. All plants will be tested for the presence of WSMV, HPDV, and BYDV. Plants from these fields will be sampled at least two more times during the current growing season. Several spray WSMV inoculation methods are being evaluated on winter wheat seedlings in the greenhouse. The most efficient method will be used to test for variation within and among several winter wheat cultivars and WSMV isolates. Virus isolates identified as WSMV are increased in the greenhouse and added to the virus collectiton. |
| 2002 | The Eastern Colorado virus (Wheat streak Mosaic Virus (WSMV, and High Plains Disease (HPDV)) survey of winter wheat was continued. Very few winter wheat plants were found with foliar virus symptoms. This was mainly due to the continued severe drought in Colorado. No HPDV isolates were identified using ELISA and only three WSMV infected plants were identified. The winter wheat seedlings sampled at various distances from fields planted adjacent to dry land corn fields were tested for the presence of WSMV and HPVD. There was a decline in occurrence of WSMV as the distance from the corn fields increased. No infected plants were found more than 60 feet from the corn fields. No WSMV was identified from plants sampled following spring. Foliar disease symptoms were difficult to find on the extremely drought stressed plants. Greenhouse WSMV experiments determined the best seedling inoculation method utilized filtered leaf extract containing carborundum and applying the inoculum to 3 week old seedlings at 5.0 pounds per square inch with an atomizer held 5 -7 cm from the leaf surface. Plants were sprayed till runoff. Continuous agitation of the inoculum yielded the best results. Three distinct WSMV strains (Nebraska, Colorado, and Kansas) were found based on symptom expression and cultivar interactions. Distinct differences in disease expression occurred among isolates in shading experiments. Light intensity is very important in symptom expression and rating for disease resistance. The less light, the longer it took for disease symptoms to appear and disease severity significantly deceased. Melaleuca oil has shown promise as a protectant against WSAM infection as well as effective in reducing the growth of Cochliobolus sativus and Fusarium graminearum. |
| 2003 | The Eastern Colorado winter wheat foliar mosaic virus (Wheat Streak Mosaic Virus (WSMV) and High Plains Disease Virus (HPDV)) survey was continued. Only one winter wheat plant with foliar mosaic symptoms was confirmed infected with WSMV by an ELISA test. The isolate did not test positive against HPDV antiserum. The severe drought in 2002 resulted in extremely low wheat leaf curl mite populations and subsequently few plants with foliar mosaic virus symptoms were found during the 2003 survey. Additional greenhouse WSMV seedling inoculation studies confirmed the importance of light intensity for symptom expression. Supplemental lighting shortened the latent period and increased symptom expression during natural short days. Shading in the summer lengthened the time until symptom expression occurred and decreased symptom severity. There were no significant differences in temperature under shade cloth and natural light. Five WSMV isolates were compared for symptom expression and symptom severity. Significant differences among the isolates occurred under shade in the summer, under supplemental lighting during the fall and winter along with significant differences when resistant and susceptible winter wheat cultivars were compared. Melaleuca oil at concentrations not toxic to wheat seedling leaves, did not affect latent period, lesion size, sporulation capacity, and infection efficiency in Cochliobolus sativus greenhouse seedling inoculation experiments. Melaleuca oil significantly reduced the growth of Cochliobolus sativus and Fusarium graminearum in culture on Potato Dextrose Agar. Higher Melaleuca oil concentrations, but below levels toxic to wheat seedlings, completely inhibited growth of both pathogens in culture. |
| 2004 | The Eastern Colorado winter wheat foliar mosaic virus (Wheat Streak Mosaic Virus (WSMV) and High Plains Disease Virus (HPDV)) survey of was continued. Seven winter wheat plants were found with foliar virus mosaic symptoms. Two of the samples were confirmed infected with WSMV by ELISA tests. The isolates did not test positive against HPDV antiserum. The effects of the severe drought in 2003 again resulted in low wheat insect populations. Few plants with foliar mosaic virus symptoms were found during 2004. Greenhouse WSMV seedling inoculation studies were initiated to determine the effect of virus infection on leaf spot disease caused by Cochliobolus sativus. Single spore inoculations were made with conidia of Cochliobolus sativus on leaves of healthy seedlings and leaves of susceptible (Tomahawk) seedlings previously infected with wheat streak mosaic virus. Time until symptom expression, lesion size, and sporulation capacity were recorded. Preliminary data suggest that prior infection with wheat streak mosaic virus increases subsequent symptom expression and sporulation capacity of Cochliobolus sativus. Higher levels of wheat streak mosaic incidence may cause an increase in disease intensity and subsequent inoculum production by Cochliobolus sativus. The higher inoculum levels could result in increased seedling blight, leaf spot, common root rot, and black head mold of wheat and barley. |
| 2005 | The Wheat Streak Mosaic Virus (WSMV) and High Plains Disease Virus (HPDV) survey of the High Plains of Colorado was conducted during spring of 2005. More plants with foliar mosaic symptoms were found than the previous three years but not as many as in pre-drought years. Eight plants with typical foliar mosaic symptoms were confirmed infected with WSMV by ELISA tests or greenhouse inoculations. No plants tested positive for HPDV. Early season moisture was closer to normal with higher insect populations than the previous three years. Greenhouse seedling inoculations with the 2005 WSMV isolates on three winter wheat cultivars revealed variation in isolate virulence and variation in symptom expression among cultivars. A range from weakly virulent to highly virulent was found among the isolates on each cultivar. There was no correlation between the location of original isolation and virulence in the greenhouse tests. The virulence range demonstrates variability in the Colorado WSMV population. This information indicates the importance of utilizing several WSMV isolates when screening for disease resistance in Colorado. |
| Impact | |
| 2000 | The populations and extent of infection by the two viruses will be evaluated for potential impact on the winter wheat crop. This information will be used to develop an integrated approach to management of the diseases that is economically efficient and environmentally sound. Studies on the pathogenic variation in the Wheat Streak Mosaic Virus population will be used to identify disease resistance and aid in its incorporation into Colorado cultivars. |
| 2001 | Data obtained from the disease surveys is being used to develop an integrated management program to control foliar mosaic virus diseases of winter wheat in Colorado. The virus isolate variation and winter wheat cultivar variation information will be utilized in the winter wheat breeding program. |
| 2002 | The virus isolate and winter wheat variety interaction information will be utilized in the disease resistance breeding program. The WSMV symptom expression variation under differing light intensity will also be useful in selecting plants with genetic resistance to WSMV. The data obtained from the Melaleuca oil seed treatment experiments may provide information in developing alternatives to fungicide protection against wheat pathogens. |
| 2003 | The data from the Melaleuca experiments demonstrated the efficacy of the oil against the dry land root rot pathogen (Cochliobolus sativus) in the laboratory. However, greenhouse tests indicate the oil would not be effective in the field. The new information on interactions among WSMV isolates, winter wheat cultivars, and light intensity will be used to refine greenhouse seedling selection techniques for genetic resistance to the viral pathogen. |
| 2004 | Monitoring the incidence of wheat streak mosaic virus, as well as other foliar mosaic virus diseases, could provide information that would result in improved prediction and management of fungal diseases of small grains. |
| 2005 | The virulence variability of 2005 WSMV isolates demonstrates the importance of using several isolates originating in Colorado when screening for disease resistance. Monitoring the incidence of wheat streak mosaic virus, as well as other foliar mosaic virus diseases, provides information that could result in improved prediction and management of diseases of small grains. |
| Publications | |
| 2001 |
Brown, W. M., Jr. and Hill, J. P. Diseases of Wheat in Colorado. Pp 24-25. In: Colorado Wheat Production Handbook. 2000. F. B. Peairs, Ed. Colorado Association of Wheat Growers. Brown, W. M., Jr., Hill, J. P., and Velasco, V. R. 2001. Barley Yellow Rust in North America. Pp. 367-384. Annual Review of Plant Pathology. Vol 39. Annual Reviews. Palo Alto, CA. |
| 2002 |
Caolo-Tanski, J. M., Hanson, L.E., Hill, A. L., and Hill J. P. 2002. Use of Melaleuca arternifolia oil for plant disease control. S12. Phytopathology. Volume 92, Number 6 June (Supplement) 2002 |
| 2003 |
The Use of Australian Tea Tree Oil, Melaleuca Alternifolia Maiden & Betche as a Method of Disease Control in Several Crop Species. 2003. J. M. Caolo-Tanski. MS thesis. Colorado State University, Fort Collins, CO. The use of Melaleuca oil for crop disease control. 2003. J. M. Caolo-Tanski, L. E. Hanson, A. L. Hill. J. P. Hill, and H,. F. Schwartz. 2003 Pacific Division of the American Phytopatholgical Society Annual Meeting, Kona, Hawaii, June 22-24. |