2020: Response Of Cotton Varieties To Inoculation With Xanthomonas Citri Pv. Malvacearum, The Causal Organism of Bacterial Blight
DR. TOM ALLEN AND DR. BRIAN PIERALIS
MISSISSIPPI STATE, MISS.
During 2020, two sets of the cotton varieties (56 entries) contained in the Mississippi State University Official Variety Trial were planted in Stoneville. At flowering (7/15/2020), plants were inoculated with a bacterial suspension that contained the bacterium that causes bacterial blight (Xanthomonas citri pv. malvacearum). Plots were inoculated in 15 gallons of water/Acre. Following inoculation, plots were observed for the presence of bacterial blight on two separate occasions (17, 26, and 34 days post-inoculation). The results contained in the attached table were based on the last observations made August 20, 2020. Plots were evaluated using a percent scale (0-100 percent) for the incidence (percentage of leaves exhibiting symptoms), severity (percentage of the leaf surface area exhibiting symptoms) and for defoliation (0-100 percent of each plot) as a result of bacterial blight. Eight total replicate plots of each variety were evaluated, four receiving inoculum (inoculated) and four that did not receive inoculum (non-inoculated). A response was assigned for each variety based on the values outlined below and the specific visual response to the bacterium.
Responses were assigned using a letter designation based on the numerical incidence response within a given range. Responses are defined as:
S = susceptible
MS = moderately susceptible
MR = moderately resistant
R = resistant
Only one variety exhibited an incidence of bacterial blight greater than 60 percent (observationally). In all, the breakdown of variety responses within the OVT were: S = 39 percent of the entries, MS = 4 percent of the entries, MR = 5 percent of the entries, and R = 52 percent of the entries. ∆
DR. Tom Allen: Extension Plant Pathologist, Mississippi State, Miss.
DR. Brian Pieralis: Assistant Professor, Mississippi State, Miss.
Response of the cotton varieties in the 2020 Mississippi State University Official Variety Trial to inoculation with the bacterial blight bacterium at Stoneville, MS.
Variety Response Variety Response
19R113 B3XF S DP 1845 B3XF R
19R132 B3XF R DP 2012 B3XF R
19R227 B3XF S DP 2020 B3XF R
AMX 19A014 B3XF S DP 2038 B3XF R
AMX 19A015 B3XF MS DP 2055 B3XF S
AMX 19A016 B3XF S NG 3522 B2XF S
AMX 19A018 B3XF R NG 3729 B2XF S
AMX 19B001 B3XF S NG 3930 B3XF MR
AMX 19B003 B3XF S NG 4098 B3XF R
BX 2151GLTP S NG 4936 B3XF MS
BX 2191B3XF S NG 5711 B3XF R
BX 2192B3XF S PHY 350 W3FE R
BX 2193B3XF R PHY 360 W3FE R
BX 2194B3XF S PHY 390 W3FE R
CP 20XAP B3XF MR PHY 400 W3FE R
CP 20XG9 B3XF R PHY 500 W3FE R
CP 9210 B3XF R PHY 580 W3FE R
CP 9608 B3XF S PX3D32W3FE R
DG 3317 B3XF S PX3D43W3FE R
DG 3427 B3XF S PX4B08W3FE R
DG 3456 B3XF S PX5C45W3FE R
DG 3520 B2XF R PX5E28W3FE R
DG 3526 B2XF S PX5E34W3FE R
DG 3615 B3XF R ST 4480B3XF R
DG 3635 B2XF S ST 5600B2XF S
DG 3799 B3XF R ST 5610B3XF S
DP 1646 B2XF MR UA114 R
DP 1725 B2XF S UA222 R
Response is presented as a letter assessment based on the percentage of plant material exhibiting disease post-inoculation. Variety responses listed above are based on disease incidence following inoculation with the bacterial blight causal organism and based on evaluations of observable disease incidence on a 0-100% scale. Responses were assessed as S = susceptible; MS = moderately susceptible; MR = moderately resistance; and R = resistant based on the observational response of each variety in a replicated variety trial planted in Stoneville, MS. Plants were inoculated with the bacterium that causes bacterial blight and evaluated for the incidence and severity that resulted from bacterial blight.