Some shedding is normal
Cotton naturally sheds a proportion of its squares and young bolls — the plant sets more than it can carry and adjusts. Up to roughly a quarter is not a problem. Panic sets in at the sight of any shedding, and the spray that follows is often the real loss.
The question is not is it shedding but why.
Pick up the shed square and look at it
This single step separates the three causes.
A hole, or a discoloured entry point, or frass. That is bollworm. Cut it open — a larva or a tunnel confirms it.
Clean abscission — the square simply detached, no hole, no rot. That is physiological: heat, water stress, waterlogging after heavy rain, or a nutrition gap.
Wet, rotting, discoloured at the base. Look at bacterial or fungal involvement, particularly after prolonged wet weather.
If it is bollworm
Check the threshold before spraying — pheromone traps for pink bollworm, and physical inspection of squares for others. At threshold, chemistries such as BOLLMASTER (emamectin benzoate + novaluron), VORTEX (flubendiamide 480%) or HAWKEYE (indoxacarb 14.5%) are the usual choices, rotated so the same group does not repeat.
Spray in the evening and cover the top third of the canopy, where the squares are.
If it is physiological
No insecticide helps, and the spray adds stress.
- Water stress at flowering is the commonest cause in rainfed cotton. Irrigate if you can.
- Waterlogging sheds squares within days. Drain.
- Boron and calcium deficiency shows up precisely at flowering, because both move poorly in the plant and demand peaks then. A foliar such as CALBOR (calcium + boron) at square formation is the standard corrective.
- Excess nitrogen causes rank vegetative growth and shedding. This is self-inflicted and very common on well-manured fields.
If the canopy has gone rank
A cotton crop that is all stem and leaf with little retention needs canopy management, not feeding. MEPIROOT (mepiquat chloride 5%) is used to check excessive vegetative growth so assimilate goes into bolls rather than branches. Timing and rate matter a great deal here — applied too early or too heavily it costs yield.
Before you fill the tank
Walk the field. Pick up twenty shed squares from five spots. Cut them open. Ten minutes of that decides whether the answer is an insecticide, an irrigation, a foliar nutrient or nothing at all.
Read the label and the leaflet before use.