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Small in size, the aphid-corn<\/a> (Rhopalosiphum maidis) requires attention from the earliest stages of cultivation. In systems that maintain corn<\/a> During the summer and off-season, the persistence of host plants and the occurrence of hot, dry periods create conditions that allow the pest to cross different growing windows and recolonize newly planted areas.\n<\/p>\n The risk is not limited to the removal of sap from the plant. In more intense attacks, the insect can cause yellowing, reduction of leaf area, curling, and drying of the leaves. Young plants, up to stages V4 and V5, are among the most susceptible.<\/p>\n There is also a second point of concern: the transmission of viruses. Aphids also produce honeydew, a sugary substance that promotes the development of sooty mold on plants. This layer can reduce the capacity for photosynthesis. When infestation occurs along with water shortages or nutritional deficiencies, productivity losses can become significant. However, there is no numerical estimate of these losses in the analyzed content.<\/p>\n The speed at which colonies form helps explain why monitoring needs to begin early. Aphids have a rapid life cycle and, under many Brazilian conditions, reproduce predominantly without mating, a process known as parthenogenesis. This favors population increases in just a few days.<\/p>\n Movement also occurs between areas. Winged individuals can be carried by the wind and reach newly emerged crops. Volunteer corn, millet, and other grasses present nearby provide food and shelter, keeping the population active between crops.<\/p>\n Corn that sprouts spontaneously after harvest can act as a green bridge for the pest. The recommendation is to eliminate these plants in fallow areas and after crops such as soybeans and cotton, in addition to reducing host grasses in borders and neighboring areas. Desiccation before planting should also aim to eliminate these sources before the emergence of the new corn.<\/p>\n Within the field, monitoring becomes particularly important between emergence and the V6 stage. Areas with a history of infestation, a high presence of volunteer corn at the edges, or those subjected to periods of drought should receive extra attention.<\/p>\n The presence of the insect alone does not determine the need for spraying. The decision must take into account the number of aphids, the proportion of plants infested, the stage of corn development, the climate, and any stress conditions. There is another indicator that should not be overlooked: natural enemies.<\/p>\n Ladybugs, lacewings, hoverflies, and parasitoids are among the organisms capable of acting on pest populations. Entomopathogenic fungi can also contribute under conditions of higher humidity. The presence of these agents should be observed during field assessments before a decision is made regarding chemical control.\n<\/p>\n This care also influences the choice of insecticides. Unnecessary applications of broad-spectrum products can reduce the population of beneficial organisms. When chemical control is necessary, the recommendation is to seek strategies that minimize this impact and alternate mechanisms of action to reduce the risk of selecting resistant aphids. Seed treatment acts as initial protection. Systemic insecticides used at this stage can protect plants in the first weeks after emergence and reduce the need for very early foliar applications.<\/p>\n This protection, however, has a limited duration. The period of action varies according to the active ingredient, the dose, the hybrid, and the soil and climate conditions. The crop needs to continue to be monitored because the infestation can increase after this effect diminishes.<\/p>\n The choice of hybrid is also part of this strategy. There are no hybrids completely immune to aphids, but materials that are more tolerant to different types of stress may perform better under pest pressure. Good leaf health and lower susceptibility to viruses are among the criteria indicated for areas with a history of the problem.<\/p>\n Summer and off-season harvests present different scenarios.<\/strong><\/p>\n The conditions faced by summer corn and the second corn crop require adjustments in monitoring.<\/p>\n In summer plantings, rainfall can help remove some insects from the plants. The situation changes when a dry spell occurs early in the development phase. Under these conditions, the recommendation is to reinforce surveillance from emergence and especially up to the V6 stage.<\/p>\n During the off-season, the generally drier and warmer environment creates favorable conditions for increased corn populations. Early control of volunteer corn, the use of hybrids adapted to stress conditions, and intensive monitoring become important during this period.<\/p>\n Staggered planting adds another challenge. When cornfields at different stages of development are close to each other, they can facilitate the continuous movement of the pest. Newer plots near more advanced crops therefore require increased vigilance.<\/p>\n When foliar insecticide application becomes necessary, it should be based on observed field conditions. In addition to the infestation level, the decision should consider the plant's growth stage, the occurrence of stress, the forecast of rain or drought, and the presence of natural enemies.\n<\/p>\n The efficiency of spraying also depends on the application technology. Spray volume, nozzle selection, and timing must allow the product to reach the areas of the plant where the colonies are located. Strong winds, very high temperatures, and unsuitable mixtures should be avoided.<\/p>\n Chemical control also requires professional guidance and an agronomic prescription. The use of personal protective equipment, adherence to the label and instructions, compliance with safety and re-entry intervals, and recording of applications are all part of the requirements for this operation.<\/p>\n For the producer, the main point is that dealing with aphids begins before any spraying. Eliminating plants that support the population between crops, monitoring the corn from emergence, observing natural enemies, correctly using seed treatment, and deciding on insecticide only when conditions indicate the need are measures that must work together.<\/p>\n In a system with summer and off-season corn, maintaining a history of occurrences and strategies adopted also helps guide decisions in subsequent cycles. Management, therefore, depends less on isolated actions and more on the ability to identify risk at the right time and combine the tools available for each field situation.<\/p>\n<\/p><\/div>\n\n<\/div>\n\n<\/div>\n\n<\/div>\n\n<\/div>\n\n<\/div>\nTHE MM Cereais<\/strong> works with the best grains on the market and also keeps you up to date with the latest news and analyses on agribusiness.
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