Location: Peanut and Small Grains Research Unit
Project Number: 3070-30400-001-001-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 5, 2025
End Date: Sep 30, 2027
Objective:
The cooperator will address the following objectives: (1) Assess effects on sorghum grain yield of whorl worm infestation in sorghum fields; (2) Determine the effects of chinch bug feeding on sorghum plant growth of lines and varieties of grain sorghum under greenhouse conditions; and (3) Develop and test a smart phone App to implement economically effective sequential sampling for sorghum headworm in grain sorghum for the Southern and Central Plains states of Texas, Oklahoma and Kansas. (4) identify sorghum entries with chinch bug resistance by screening available sorghum seed sources, lines, and varieties. (5) Conduct greenhouse studies of effects of sorghum whorlworm feeding on growth and yield of grain sorghum. (6) Determine the role of spatiotemporal variation in natural enemies on aphid pest severity and biological control in grain sorghum. 7) Determine the potential of multispectral data acquired by UAV for monitoring whorlworm and sorghum aphid infestations in grain sorghum.
Approach:
Resistance Evaluations in a greenhouse will use a combination of choice and no-choice experiments to evaluate prospective sorghum entries for the three functional categories of resistance, tolerance, antibiosis, and antixenosis. There are no sorghum hybrids with documented chinch bug resistance, but there are known susceptible sorghum hybrids, including TX 7000 and KS 585, which will be planted as checks among sorghum entries for all three experiments. The number of sorghum entries evaluated will depend on identifying prospective resistant entries and on the number of entries we have the capacity to test. All experiments for this study will be conducted in a greenhouse maintained at temperature of 21-31o C and photoperiod of 14:10 L:D. For objective 5) replicated trials will be conducted in a greenhouse where plants will be subjected to mechanical damage simulating whorlworm feeding at different intensities. Growth parameters, and plant grain yield will be measured on plants. Results will be subjected to statistical analysis. For objective 6) the experimental design for this study is similar to many studies of landscape scale phenomena where study areas (fields in this case) were selected to provide broad coverage of a geographic area of interest. Populations of aphids and their natural enemies were estimated during the sorghum growing season in 35-40 sorghum fields each year. Each field is an experimental unit, and each field was sampled weekly an average of 6 times. Statistical analysis will involve use of regression to model the relationship between natural enemy density and sorghum aphid population growth. We will use regression models to determine thresholds at which aphid mortality caused by natural enemies will maintain aphid population density below economic threshold levels in sorghum. For objective 7, sorghum will be planted in Oklahoma within which we will manipulate densities and injury caused by sorghum aphid and sorghum whorlworm. Multi-spectral imagery will be obtained by a multispectral camera with wavelength bands in the blue, green, red, and NIR. The camera will be mounted on a commercially obtained UAV. Each pixel in an image will contain a digital number for each of the bands recorded by the camera. We will compare the mean number of sorghum aphids per replicated plot to reflectance intensity in the imagery. We will also compare the mean plant damage index for whorlworm per replicated plot to reflectance intensity in the imagery. Several vegetation indexes will be calculated from bands of multi-spectral data, which are known for utility in detecting variation in plant health in multi-spectral imagery. We will statistically assess the relationship between the vegetation indices and sorghum aphid density and mean whorlworm damage rating in plots using correlation and regression methods. Regression coefficients will be tested for significance using F-tests for full and reduced models. Appropriate SAS and R procedures were used for all statistical analyses. The goal of the research is to develop reliable methods for determining sorghum plant injury for the purpose of making pest management decisions.