Contributed by: Christy Hicks, Regional Extension Agent, Agronomic Crops
December 12-13 – Auburn University Row Crop Short Course
Last Effective Bloom Date for Cotton
The last effective bloom date is the calendar date you normally expect a bloom to have time to fully mature into a boll. The estimated date for Central AL is September 5th. Cotton needs at least 4 weeks of bloom. A cotton crop needs to be at first bloom no later than August 9th in our area. As you know every growing season is different, however using the last effective bloom date can provide information on the risk and potential of a cotton crop.
Many fields in the area have Fusarium Wilt. Affected plants are first darker green and stunted, followed by yellowing of the leaves and loss of foliage. First, symptoms appear on lower leaves around the time of the first flower. The leaf margins wilt, turn yellow, then brown, moving inward. Infected plants fruit earlier than normal with smaller bolls that open prematurely. A diagonal cut across the stem will reveal vascular discoloration.
(Picture below from on-farm variety trial)
Timing of Harvest Aid in Soybeans
When 65% of the pods are mature color, and 70% defoliation, they should be ready to desiccate. You can also collect pods from the top third of the plant at random across the field. Open the pods and look for separation of beans from the white membrane inside the pod. If this is observed, the seeds have reached physiological maturity and have reached their maximum dry weight. Yield will not be lost.
Target Spot in Soybeans
(info from Tom Allen, MSU)
Target Spot has been detected in some soybeans fields this year. Target Spot is a soil-borne fungus, moved by wind and rain. It can overwinter on crop residue. Target Spot starts in the lower canopy, unlike Frog Eye that is primarily in the upper canopy. Lesions on leaves are reddish brown, circular and variable in size up to ½” in diameter. Spots may also be found on petioles, stems, and pods. Larger lesions often show a distinct concentric zone of dead tissue and may have a narrow, indistinct yellow halo. Severe infections may cause premature defoliation.
The environment is the main ingredient that determines the severity of Target Spot. The amount of rainfall and duration of rainfall events at specific growth stages has a lot to do with if the disease will cause a yield loss. Defoliation during the mid R5 growth stage would cause significant yield loss.