What to Do About Garlic Yellowing? Cause Analysis and Control Methods
Anyone who has grown garlic has likely encountered the phenomenon of garlic yellowing. Especially in recent years, due to the influence of various factors in production, garlic yellowing has been particularly prominent, leading to reduced garlic yields and a serious decline in the quality of the harvested garlic. As the garlic planting season is currently underway, what causes garlic yellowing and how to prevent it have become key concerns for many farmers.
When garlic turns yellow, the main causes are improper fertilizer and water management and soil acidification. In reality, however, garlic yellowing is more likely caused by pests and diseases, especially root-knot nematode disease, which has been particularly severe in recent years. Root-knot nematode disease is caused by nematodes infecting crops. Root-knot nematodes harm a wide variety of crops, including fruit trees, cucurbits, solanaceous vegetables, and legumes, and garlic is no exception.
According to experts, in recent years, with the adjustment and upgrading of China's agricultural structure, combined with the influence of traditional planting patterns and limited arable land, the multiple cropping index of crops has generally been high. Some plots have grown vegetables, cucurbits, and other nematode host plants for a long time, and root-knot nematode damage has been severe, leaving a large amount of inoculum in the soil. Garlic is often rotated or intercropped with these host plants, which has led to the occurrence of garlic root-knot nematode disease, and it is even more serious in greenhouses, plastic tunnels, and protected cultivation. According to observations, when the second-stage juveniles of garlic root-knot nematodes attack garlic, they pierce the young parts of the fibrous roots (root tips) with their sharp stylets. The root knots hinder the roots' absorption of nutrients and water, and root growth is blocked, often resulting in no new roots being produced. Above ground, the symptoms of diseased plants are not obvious in the early stage of damage, but as the disease develops, they gradually show weak growth, pale yellow-green leaves, and spreading leaves, similar to the symptoms of water and fertilizer deficiency. As the disease progresses, the diseased plants gradually turn yellow, wilt, and even die.
It can be seen from this that preventing garlic yellowing is inseparable from the control of garlic root-knot nematodes. Experts say that controlling root-knot nematodes requires emphasizing prevention over treatment, with prevention as the priority. Preventive measures can include agricultural and physical control methods, while eradicating root-knot nematodes requires the combined use of chemical formulations to achieve the best control effect. In terms of pesticide selection, farmers can choose Yinghui nematicides. It is understood that Yinghui nematicides include products such as Ligen Sha, Yinghui Kuaixian, and Tiandixian, which target different growth stages of garlic and are available in both granular and liquid formulations. They can be used at different growth stages of garlic, with quite outstanding control effects. Before transplanting garlic, farmers can apply Yinghui nematicide granules in furrows, in holes, or broadcast over the whole field, with a duration of up to 2-3 months; if garlic is harmed by root-knot nematodes during the growing period, Yinghui nematicide liquid can be diluted with water and used as a root drench or applied by flushing.
Compared with the effects of uncontrollable factors such as drought, flood disasters, and extreme weather, the control of controllable disasters such as pests and diseases is more important for farmers and can also be prevented more effectively through human intervention. We will continue to follow and update related content to provide more help to farmers.