The last week of April and first week of May were extremely dry in some portions of west TN causing producers to chase moisture and plant seed deeper than usual. Heavy rain in some areas follwing planting on May 7th caused some soil surface sealing and crusting. Each year many producers are forced to replant cotton due to adverse conditions. Replanting is one of the most difficult decisions to make and second guessing is very common.
The recommended planting window for Tennessee is April 20-May 10. Although boll weevil eradication, Bt cotton and early-maturing varieties may have extended the planting window, but planting after May 20 is beyond the optimum planting window for high yields. A poor stand may be replanted on May 1 but will more likely be kept on May 20. Regardless of the advances in technology, an early freeze can be devastating to an immature crop (Table 2.). Setting a two bale crop on the plant and harvesting that same cotton are two different things.
Evaluate the existing stand
Go to at least 10 places within the field and measure 1/1000th of an acre. For example, 13 feet, 9 inches is 1/1000th of an acre for 38” rows. For more row spacings see Table 3. Once the desired length has been measured, count the number of plants. Multiply the number of plants X 1000 to determine your plant population per acre. Remember, go to several places and count not only the number of plants but also observe your stand for uniformity. Take note of any skips longer than three feet in length. Once this has been done, you then have to make the decision about plants that will live and those that will die. If the plant has severe lesions on the stem and the plant is brittle, it will probably die. If the roots are discolored but remain white or green when the brown tissue is scraped away, it will probably live. Also, examine the plant terminal. How do the new leaves look? If there appears to be new growth emerging, the plant may live. If the plant looks sick and you can’t make a decision, assume it will die. However, cotton has a tremendous ability to survive and compensate during the growing season if conditions improve.
How many plants are needed to make a crop?
Research has shown that cotton yields are similar when uniform populations of 20,000-70,000 plants per acre. Uniform populations are critical and fields with large skips may need to be replanted. What is the yield potential of the field? Fertile, bottomland fields may have more compensation ability than eroded, droughty hills. Remember when it’s getting late in the planting season yield potential is decreasing every day. Uniform populations of 1-2 plants per foot (Table 4.) may not be ideal, but can be satisfactory provided the stand in UNIFORM.
What are your costs and what cultural practices have been used?
Sometimes replanting to cotton is not the best option. However there are several factors that will determine this decision. Has a residual herbicide been applied? Some herbicides like Cotoran, Caparol or Diuron will essentially lock you into cotton due to labeled re-plant restrictions. Is the land leased or under a gin contract? Lease agreements are often crop specific and offer no alternatives. Also, the type of rental agreement can play a role. Extremely high rent may not allow a grain alternative. Has fertilizer been applied? Another factor that has become more important in recent years is the technology fee. Before replanting, determine whether the additional technology fees will be rebated. Another factor to consider if replanting to a different crop is that payments in the current farm bill are decoupled from production, thus payments are made regardless of crop planted.
Manage for earliness
Choose an early maturing variety with Bt technology if you decide to replant. If the stand was lost due to disease, use the full rate of fungicide when replanting and try to plant beside the old row. The old furrow will contain disease inoculum and conditions for disease can be worse than the initial planting. It is imperative to achieve a uniform stand with this planting because time is precious. Fields that are not replanted will likely be stunted. Fruit retention will be crucial, as time may not allow for late season blooms to mature. In addition to early square retention, timely mepiquat chloride (Pix, Pentia, Mepichlor, Mepex, etc.) or Stance applications will help improve earliness. If the stand is partially lost to hail, some of these plants with damaged terminals may lose apical dominance and become “crazy”. This vegetative growth will need special care in order to achieve good fruiting and earliness. In cases when the decision to replant is made, match the correct nitrogen rate to the realistic yield potential of the late planted crop. Adding more nitrogen than necessary will delay maturity and increase the potential for losses from late season weather changes.
Other points to consider:
Weather forecast. Does the 5-7 day forecast look promising? Will conditions be conducive to plant growth or rapid germination and emergence? Weather forecast can play a big role in replant decision making. If the decision to replant is made, destroy the old stand. Plants from the first planting will mature differently and will compete with the replanted population. Some control options are:
- 32-40 oz Gramoxone SL
- 32-40 oz Gramoxone SL + 32 oz Cotoran or Caparol
- 32-40 oz glufosinate (non-Liberty Link and non-WideStrike varieties only)
- 32-40 oz glufosinate + 32 oz Cotoran or Caparol
- 22-32 oz Glyphosate for Liberty Link or non-glyphosate cotton
Should the whole field or portions of the field be replanted? Spot re-planting is a means of reducing seeding costs and time. However, this often complicates crop management since several maturity ranges will be found within one field. If spot planting, try to block out parts of the field so that management inputs can be directed to larger areas. Also, choose varieties whose growth habits and maturity will closely follow the first planting.
Remember that cotton is very forgiving and you can make acceptable yields with a late planted crop. Once you make the decision to either replant or not you must believe that you have made the correct decision and do everything to ensure its success. A common rule of thumb among most university Extension specialists is “If the decision to replant is difficult, then there are probably enough plants to keep the stand.”