Causes and control of yellow wheat seedlings

The causes of yellow wheat seedlings are as follows: soil preparation is not fine enough, base fertilizer is not mature enough, seed dressing pesticide concentration is too high, sowing density is too high, no base fertilizer is applied or insufficient fertilization, soil stagnant water, occurrence of diseases and insect pests, cold wave cooling and so on. Prevention and control methods of wheat yellow seedlings: the first choice is to accurately judge what causes the yellow seedlings, and then take remedial and control measures according to the specific causes of the yellow seedlings.

1. Rough yellow seedlings

Reason: if the soil preparation is not fine enough, there are more large pieces of soil in the soil, and the soil is too soft, resulting in poor root system, which will make the seedlings grow slowly, yellow leaves, shrink heart and weak seedlings.

Prevention and control method: crush the covered soil as soon as possible, and then water the hoe.

Second, fat and yellow seedlings

Reason: if the base fertilizer is not fully mature, the seeds and seedlings are prone to burn after they come into contact with these fertilizers, resulting in yellowing of leaves and leaf tips.

Prevention and cure: it can be watered immediately, during which it can be watered once a day for several days.

Third, drug damage to yellow seedlings

Reason: if the concentration of pesticide in seed dressing is too high, the root tip will be injured and enlarged and yellow seedlings will appear.

Prevention and control methods: if the yellow seedlings are not serious, there is no need to deal with them. When the secondary roots grow out, the seedlings will gradually turn from yellow to green, and if the yellow seedlings are more serious, they need to be watered immediately and the soil should be loosened after watering.

IV. Over-dense yellow seedlings

The reason: the wheat fields with early sowing time and large sowing amount often appear that the seedlings grow too vigorously and the density is too high, and the seedlings turn yellow because of poor nutrition and poor growth.

Prevention and control methods: it is necessary to press the soil in time to make the seedlings grow slowly and healthily, and to deeply plough and cut roots, control the growth of tillers, and the excessive growth of small tillers. At the same time, attention should be paid to timely seedling thinning and topdressing in an appropriate period. Paclobutrazol chemical control can be used in serious cases.

Fifth, lack of fertilizer yellow seedlings

Reason: when sowing, there is no time to apply base fertilizer or insufficient fertilization, and there is no timely topdressing in the later stage, the seedlings will turn yellow because of long-term lack of nutrition.

Control method: applying chemical fertilizer before winter, applying ammonium bicarbonate 25-30kg and phosphate fertilizer 15-20kg per mu can promote early tillering and early secondary rooting.

VI. Dry yellow seedlings

Reason: in case of dry climate or lack of soil water, the seedlings will grow slowly, the leaves are gray-green, the heart leaves grow slowly, the basal leaves turn yellow, the secondary roots are few, and the tillering is difficult.

Prevention and control methods: timely watering and fertilization is needed to promote the normal growth of seedlings and more strong tillers.

7. Yellow seedlings damaged by waterlogging

Reason: planted in fields with low-lying terrain and poor ditching and drainage, because they are in a waterlogged state for a long time, organic matter will decompose slowly, nutrients can not be absorbed in time, resulting in yellowing leaf color, slow growth, hindered root growth, shallow roots, and in serious cases, rotting roots and dead seedlings.

Prevention and control methods: it is necessary to do a good job in clearing ditches and drainage measures, dredging the field drainage ditches in time, lowering the underground water level, and then applying a small amount of available nitrogen fertilizer, phosphate fertilizer and potassium fertilizer to promote the revival of seedlings.

8. Yellow seedlings of insect pests

Reason: when wheat aphids and spiders occur, they will absorb the sap of the leaves and cause the leaves to turn yellow. When mole cricket, golden needle worm and other underground pests occur, they will bite the roots of seedlings, resulting in yellowing leaves, and in serious cases, they will directly bite off the roots and cause seedling death.

Control method: 65-75ml 40% omethoate EC can be used per mu, 50kg can be sprayed with water, or 50% phoxim EC or 40% methyl iso-parathion EC can be used for root irrigation.

9. Diseased yellow seedlings

Cause: rust, total erosion disease, sheath blight and other hazards will lead to yellowing and weakening of seedlings.

Control methods: chemicals can be used to control sheath blight. 150g / mu of 20% triadimefon EC, or 50-75g carbendazim 50% wettable powder, or 150g-200g 5% Jinggangmycin water agent, 50-75kg water spray, rust can be sprayed with 1000 times liquid 15% triadimefon wettable powder, and total erosion disease can be sprayed with 15% triadimefon EC and 50-60kg water.

10. Cold injury to yellow seedlings

Reason: when wheat seedlings emerge, if you encounter a cold wave to cool down, it is easy to cause chilling injury, which will lead to sudden yellowing of tender tips and leaf tips, or damage to some tissues of leaves, which will gradually turn yellow in the later stage.

Prevention and control methods: watering before the arrival of the cold current, strengthening the management work after the cold current, and spraying foliar fertilizer.

11. Salt damage to yellow seedlings

The reason: when the soil salt content is relatively high, it will easily lead to the growth of wheat plant thin and short, few tillers, narrow leaves, more yellow leaves at the base, yellow-green leaves and purplish red leaf tips.

Prevention and control methods: timely ploughing and loosening the soil, reducing surface water evaporation and avoiding salt return. If possible, irrigation and salt washing or trenching can be adopted to reduce the soil salt content.