Some High Plains cotton producers, most every year, must decide whether to leave damaged cotton stands in the field, hoping for recovery and acceptable yield potential, or to start over, investing more time and money to replant.
“When poor seedling emergence and stand reductions result from such conditions as low temperatures, excessive soil moisture, packing rains, wind and sand abrasion, hail, or seedling diseases, replant decisions must be made,” said Randy Boman, Extension agronomist with Texas AgriLife Extension Service at Lubbock.
“To aid producers in making these replant decisions, we discuss several topics: remaining stand, stand uniformity, crop condition, calendar date, and costs versus benefits of replanting. We also include an example of decision making, and suggestions for replant management.”
The optimum plant density for cotton ranges from about 25,000 to 50,000 plants per acre (about 2 to 4 per row-foot) in 40-inch row spacing. However, after a weather event, if the plants are uniformly spaced, populations as low as 13,000 to 26,000 plants per acre (1 to 2 per row-foot) can produce acceptable yields.
“It's usually best to delay final stand evaluation until after the crop is exposed to two or three days of good growing conditions. In the meantime, timely tillage of crusted fields should be performed to minimize wind and sand damage, improve aeration, and hasten warming and drying of the soil, which will retard development of seedling disease,” Boman said.
“After a reasonable period, if two or more healthy-appearing plants remain per foot of row, and there are not too many long skips, the stand is likely adequate to make near optimum yields. However, if this is not the case, additional evaluations are needed.”
Plant-spacing uniformity is a critical consideration in replant decisions and the more uniform the plant spacing, the greater the yield potential. Skips in the row may cause significant yield reductions even though the average number of plants per acre may be adequate for acceptable lint yields.
Plants cut off below the cotyledonary nodes will not survive, and plants with deep stem bruises may die or only partially recover. Plants without terminals may survive if they have viable buds, and if the stem area below these buds is intact.
If stem damage is minimal, any remaining viable leaf tissue will increase the chance for survival and hasten recovery.
“Plants subjected to long periods of adverse growing conditions often become infected with seedling diseases that affect roots, vascular system, and leaves,” Boman said.
If tap roots develop a black, water soaked appearance, they are diseased and further deterioration will probably occur. On the other hand, if the tap root is intact and the outer covering of the root (though discolored) has hardened, chances of recovery improve.
“If weather conditions remain marginal, count only the healthiest plants as potential survivors. With improved growing conditions, a larger percentage of plants showing signs of recovery will survive and develop into productive plants,” Boman said.
“Producers are rightly concerned about how much their yield potential will be lowered if they choose to replant cotton after the optimum time,” Boman said.
“Data obtained in the High Plains in the 1960s and 1970s demonstrated that cotton planted on June 1, June 10 and June 20, yielded 8 percent, 24 percent and 49 percent, respectively, less lint than cotton planted on May 15. Although the data is somewhat dated, it is still probably a good guideline.
“In addition to lower yield potentials, later plantings often result in reduced fiber quality, delayed harvest and increased harvesting costs. High Plains research showed that micronaire, lint percentages and color grades tended to decrease as planting dates were delayed beyond the optimum.”
Replanting incurs additional costs for seed, labor, and machinery use. In some instances, replanting may also require additional inputs for irrigation, herbicides, insecticides, and fungicides. Other considerations may include crop insurance, farm program options, and the yield-price outlook for alternative crops.
“Many seed companies now provide highly beneficial replant programs to producers in some areas. Check with seed and technology provider representatives for available programs,” Boman said.
“The decision to replant or save the existing crop may require integration of the best available field and research data,” Boman said. “For example, consider a crop in the High Plains that has a skippy, 50 percent stand. Research indicates the grower could expect yield losses of 25 percent to 30 percent compared to a normal stand. If the replant decision has to be made around June 1, research results indicate that he could expect only a 7 percent to 10 percent yield decrease by planting on that date. In this case, the field should be replanted. On the other hand, if the replant decision had to be made around June 15, the expected percent yield loss would be about 36 percent, and the producer would probably do better to keep the existing stand.
“Cotton has a tremendous capacity to recover from adverse situations. After an assessment of the existing crop, if there is some doubt about replanting, it's usually best not to replant.”
To maximize yield potential of the replanted crop, the following suggestions should be considered:
Plant earlier maturing varieties.
If necessary, replant with a “buster-type” planter so the cotton seed can be planted in a herbicide-free zone.
Plant high quality, fungicide-treated seed at recommended rates.
Adjust nitrogen for yield potential.
Adjust irrigation water to enhance early fruit retention and regulate cut-out.
Protect crop from insect damage.
Alter management strategies to match the probable growing season.
Additional information about cotton replanting, and possible alternate crops, is available at http://lubbock.tamu.edu/. A good publication on making replant decisions is available at: http://lubbock.tamu.edu/cotton/pdf/makingreplantdecisions07.pdf.