Peanut management should focus on early leaves

The late growth stage of peanuts refers to the period from the first full fruit pod to the mature harvest, typically lasting around 45 to 55 days. During this time, the plant no longer produces new leaves, and the lower and middle leaves begin to drop. The primary focus of field management during this phase is to prevent early leaf loss, particularly in the upper leaves, to maintain a large green leaf area and extend the functional life of the foliage. This helps increase the number of effective pods, enhance pod filling, and ultimately boost overall yield. Early defoliation in peanuts can be caused by several factors, including over-fertilization, premature aging, and more severe conditions in sandy soils. Another major cause is leaf spot diseases, especially black spot and brown spot, which spread rapidly and can lead to significant leaf loss within just a few days. Additionally, excessive or improper use of plant growth regulators, such as long-acting ones like paclobutrazol, can also contribute to early leaf drop. To prevent this, it's crucial to focus on disease prevention and proper nutrient management. One of the key strategies for preventing leaf spot disease is timely application of fungicides. Peanut leaf spot disease includes black spot and brown spot, both of which primarily affect the leaves. Symptoms usually start from the lower leaves and gradually move upward. In the early stages, brown spots appear, which then develop into round or irregular lesions. Brown spot lesions are larger with yellow halos, while black spot lesions are smaller, lighter in color, and have neat edges without a halo. Under wet or prolonged rainy conditions, these lesions may merge into large, irregular spots, leading to leaf scorching and reduced photosynthesis. If the disease affects the petiole, stem, or fruiting pegs, it can result in dark, elliptical lesions that eventually kill the affected parts, significantly lowering peanut yields. The main culprits during the late growth stage are brown spot and net spot diseases. Early application of appropriate fungicides is essential. Recommended treatments include an 80% mancozeb solution diluted at 800 times, a 70% methyl thiophanate solution at 800–1000 times, agricultural anti-120 water agent at 200 times, a 50% colloidal sulfur solution at 200 times, or a 1:2:200 Bordeaux mixture. Spraying should be done thoroughly, avoiding missed areas, and repeated every 8–10 days, with up to 3–4 applications needed to effectively control the disease. Another important practice during the late growth stage is foliar fertilization. As the root system’s ability to absorb nutrients declines, the leaves become more efficient at nutrient uptake. Foliar sprays offer fast absorption, quick action, and high efficiency, making them an excellent way to prevent premature aging and leaf drop. For sandy soils, thin soil, or plants showing signs of nutrient deficiency such as yellowing leaves, a 1% urea solution can be applied. However, for fields with strong vegetative growth, urea may not be necessary. Phosphorus absorption by peanut leaves is very effective, so applying a 2–3% superphosphate leaching solution (prepared by soaking for 14–16 hours) at 60 kg per acre, sprayed every 7–10 days for 2–3 times, can increase yields by 7–10%. Alternatively, 100–150 g of potassium dihydrogen phosphate per acre mixed with 50 kg of water can be sprayed in the evening or on cloudy afternoons. It should be applied three times, once every seven days, and if rain occurs within eight hours, reapplication is necessary. Peanuts are highly sensitive to iron deficiency, especially in alkaline soils, where yellowing and whitening of leaves may occur. Applying a 0.2% ferrous sulfate solution every 5–6 days for 2–3 times can quickly restore green color to the leaves.

Rotary Forging Die

Rotary forging die

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