A Detailed Explanation of the Occurrence Patterns and Control Methods of Wheat Take-All Disease
The Occurrence and Control of Wheat Take-All Disease
Wheat take-all is a root disease. After heading, a black plaster-like mycelium forms on the 1st-2nd nodes of the stem base, which is why it is also called black foot disease. This fungus has a relatively broad host range and can infect more than 10 species of cultivated or wild grasses. After wheat is harmed by take-all, it shows reduced tillering, a low rate of earbearing tillers, and decreased thousand-grain weight, and in some cases late-stage sterile ears or dead white ears form. Lightly affected fields generally see a yield reduction of 10-20%, while severely affected fields see reductions of over 50%, or even total crop failure.
I. Main identification symptoms:
At the seedling stage, diseased plants are short and stunted, with many yellow lower leaves, and the seed roots and underground stem turn grayish-black; in severe cases, this causes patchy death of wheat seedlings. At the jointing stage, overwintering diseased wheat seedlings green up slowly and have few tillers, and most of the diseased plant roots turn black. At the heading and grain-filling stages, diseased plants appear in clusters or patches as early-withered white ears, and a "black plaster"-like black mycelial layer forms on the inner side of the leaf sheath at the stem base, making it very easy to identify. This is also the main symptom that distinguishes it from other wheat root diseases.
II. Transmission routes and disease occurrence conditions:
The wheat take-all pathogen is a soil-borne fungus. The fungus mainly overwinters and oversummers as mycelium left in diseased residues in the soil. It is the main source of infection for the following wheat crop. Shortly after the seeds germinate following autumn sowing of wheat, the summer fungal mycelium can attack the seed roots and overwinter within them. When wheat greens up the following spring, the mycelium also grows faster as temperatures rise, extending upward to the tillering node and stem base; from jointing to heading, it can infect up to the 1st-2nd nodes. Diseased plants mostly die successively during the grain-filling stage, producing white ears; when dry hot winds occur, diseased plants die more rapidly. The development temperature range of the wheat take-all pathogen is 3-35°C, with an optimum temperature of 19-24°C. Soil properties and tillage management conditions have a relatively large impact on take-all. Generally, loose-textured soil with low fertility and alkaline soil have more severe disease occurrence. When wheat is sown too early in autumn, moist soil favors disease occurrence and spread. Varieties with well-developed root systems are more resistant to the disease, and increasing the application of decomposed organic fertilizer can reduce disease occurrence. The influence of climate. Heavy rainfall before winter, relatively high temperatures during the overwintering period, and warm, rainy spring conditions all favor the occurrence of this disease.
III. Control methods:
1. Prohibit the introduction of seeds from diseased areas to prevent the spread of the disease, and do not exchange or use self-saved seed from diseased fields. 2. Crop rotation. Implementing wheat-cotton and wheat-vegetable rotation, or switching to crops such as soybean and peanut, can significantly reduce disease occurrence. 3. Increase the application of decomposed organic fertilizer. 4. Sow wheat at the appropriate time but later, to shorten the effective infection period. 5. Chemical control.
(1) Use 0.8% penconazole·hymexazol suspension concentrate to dress wheat seed at a 1:3 ratio; after dressing, pile and cover for 3-4 hours or air-dry before sowing. While controlling wheat take-all, it can also control diseases such as root rot and smut.
(2) Use 50-100 ml of 3% difenoconazole plus 10-20 ml of 2.5% fludioxonil, or use 20-40 ml of 12.5% silthiofam aqueous suspension concentrate mixed with 150 g of water to dress 10 kg of wheat seed. Sow immediately after dressing.
I. Main identification symptoms:
At the seedling stage, diseased plants are short and stunted, with many yellow lower leaves, and the seed roots and underground stem turn grayish-black; in severe cases, this causes patchy death of wheat seedlings. At the jointing stage, overwintering diseased wheat seedlings green up slowly and have few tillers, and most of the diseased plant roots turn black. At the heading and grain-filling stages, diseased plants appear in clusters or patches as early-withered white ears, and a "black plaster"-like black mycelial layer forms on the inner side of the leaf sheath at the stem base, making it very easy to identify. This is also the main symptom that distinguishes it from other wheat root diseases.
II. Transmission routes and disease occurrence conditions:
The wheat take-all pathogen is a soil-borne fungus. The fungus mainly overwinters and oversummers as mycelium left in diseased residues in the soil. It is the main source of infection for the following wheat crop. Shortly after the seeds germinate following autumn sowing of wheat, the summer fungal mycelium can attack the seed roots and overwinter within them. When wheat greens up the following spring, the mycelium also grows faster as temperatures rise, extending upward to the tillering node and stem base; from jointing to heading, it can infect up to the 1st-2nd nodes. Diseased plants mostly die successively during the grain-filling stage, producing white ears; when dry hot winds occur, diseased plants die more rapidly. The development temperature range of the wheat take-all pathogen is 3-35°C, with an optimum temperature of 19-24°C. Soil properties and tillage management conditions have a relatively large impact on take-all. Generally, loose-textured soil with low fertility and alkaline soil have more severe disease occurrence. When wheat is sown too early in autumn, moist soil favors disease occurrence and spread. Varieties with well-developed root systems are more resistant to the disease, and increasing the application of decomposed organic fertilizer can reduce disease occurrence. The influence of climate. Heavy rainfall before winter, relatively high temperatures during the overwintering period, and warm, rainy spring conditions all favor the occurrence of this disease.
III. Control methods:
1. Prohibit the introduction of seeds from diseased areas to prevent the spread of the disease, and do not exchange or use self-saved seed from diseased fields. 2. Crop rotation. Implementing wheat-cotton and wheat-vegetable rotation, or switching to crops such as soybean and peanut, can significantly reduce disease occurrence. 3. Increase the application of decomposed organic fertilizer. 4. Sow wheat at the appropriate time but later, to shorten the effective infection period. 5. Chemical control.
(1) Use 0.8% penconazole·hymexazol suspension concentrate to dress wheat seed at a 1:3 ratio; after dressing, pile and cover for 3-4 hours or air-dry before sowing. While controlling wheat take-all, it can also control diseases such as root rot and smut.
(2) Use 50-100 ml of 3% difenoconazole plus 10-20 ml of 2.5% fludioxonil, or use 20-40 ml of 12.5% silthiofam aqueous suspension concentrate mixed with 150 g of water to dress 10 kg of wheat seed. Sow immediately after dressing.