Assess your understanding of common growth issues that can affect cotton crops, including pests, nutrient deficiencies, and environmental challenges. Improve your decision-making for healthier, more productive cotton fields.
A cotton farmer notices the older leaves turning yellow with green veins while the new leaves remain green. Which deficiency is most likely causing this symptom?
Explanation: Magnesium deficiency typically appears as interveinal chlorosis (yellowing between green veins) on older leaves because magnesium is mobile in plants. Nitrogen deficiency also causes yellowing but affects the whole leaf, not just between veins. Potassium deficiency often manifests as leaf edge scorching rather than interveinal yellowing. Phosphorus deficiency usually leads to dark, purplish foliage rather than yellowing.
What is a common effect of severe water stress during the cotton boll development stage?
Explanation: Severe water stress during boll development often leads to smaller bolls and shedding (dropping) of bolls, reducing yield. It does not increase fiber strength; in fact, fiber quality may decline. Water stress generally results in leaf wilting or yellowing, not increased greening. Seed viability is usually reduced, not improved, under severe stress.
Which visible sign is most likely to indicate a whitefly infestation on cotton plants?
Explanation: Whiteflies excrete honeydew, a sticky substance, which can cover leaves and attract molds. Powdery mildew is a fungal disease, not a sign of insect pests. Sunken brown lesions are typically symptoms of bacterial or fungal infections. Galls usually form due to mites or some insects, but not whiteflies.
What is a possible negative effect of applying too much nitrogen fertilizer to a cotton crop?
Explanation: Excess nitrogen promotes vegetative growth, leading to delayed maturity and excess foliage which can shade bolls. Early boll opening is not caused by too much nitrogen. High nitrogen does not improve drought resistance and can actually exacerbate water stress. Leaf disease risk can increase due to denser canopies retaining more moisture.
If cotton plants exhibit stunted growth with shallow root systems, which field issue might be responsible?
Explanation: Soil compaction limits root penetration, causing shallow roots and stunted plant growth. Healthy loam soil generally promotes strong root systems. Over-irrigation can cause root rot but not specifically shallow roots from compaction. Excessive pruning is not a common practice or a cause of shallow roots in cotton.