What s going on with the yellow brown dots on top of the green onions

Garlic and green onions are mostly normal during the growth period due to yellowing of leaf tips. Generally speaking, after the garlic and onion "rotten mother", the plant growth is accelerated, the nutrients required increase sharply, and the nutrients in the garlic and onion have been exhausted, at this time, the growth of garlic and onion needs to rely on the root system to absorb nutrients, and organic nutrients are produced by leaf photosynthesis. This usually occurs on the lower 1-4 leaves of the plant, and is generally not present on newly extracted leaves.

This can be prevented by selecting improved varieties and strengthening cultivation management.

In recent years, some onion and garlic crop planting bases, such as Xuzhou and other places, due to the heavy planting year after year, the occurrence of diseases has increased year by year, causing yellowing of leaves. There are many kinds of diseases involved, and there are bacterial and fungal diseases, even if you know what kind of disease it is, the effect of drug prevention and control after the onset of the disease is not very good. Common ones are leaf blight, blight, etc.

In production, it is best to adopt the method of crop rotation for these diseases. In the production base, it is not very convenient to change crops, so the method of water-upland rotation (such as rice-garlic rotation) should be used as much as possible to reduce the occurrence of onion and garlic diseases. In the early stage of the disease, leaf blight can be controlled with promethexin, Dasheng, Fuxing, and Shigao drugs; The disease can be prevented and treated with drugs such as Anker Manganese-Zinc, Pulik, Kelu, and Frosturea Manganese-Zinc.

The main reason for the yellowing and dry tip of the green onion leaf is that the leaf blight is aggravated due to repeated stubble. The main control measures are crop rotation and stubble. It is best to rotate crops with water and dry, or to plant other low-growing vegetables such as honey squash.

The second is to take pesticides for prevention and control. Before draining the green onions, the green onion seeds were soaked with the anti-heavy stubble agent "Enyibi"; When draining green onions, use "Enyibi" mixed with water to set the roots; After the disease is found, spray it with 75% chlorothalonil or 80% spray gram 500 times liquid (or promexin, Dasheng, Fuxing, Shigao, Dixone and other agents) in the early stage of the disease, once every 7 10 days, spray 3 or 4 times in a row, which can have a certain control effect.

There are the following reasons for the appearance of yellow spots in summer planting of shallots, which can be treated.

1. Dry yellow. The yellow of lack of water is different from the yellow of water, the yellow of lack of water is the withering and dry leaf tips or edges, and the old leaves are withered and yellow from the bottom to the top, but the growth of new leaves is relatively normal. Pay attention to watering when watering enough, water thoroughly.

Second, lack of fat yellow.

It is manifested in the color of young leaves becoming lighter, yellow or light green, while old leaves are more normal or gradually turning from green to yellow. It is necessary to check the potting soil frequently, if there is a dry knot phenomenon, the soil should be replaced, and the thin fertilizer should be applied diligently, and some alum water should be poured in a timely manner to replenish iron.

Third, the lack of light yellow.

If the leaves are shaded for a long time, the leaves will not get enough sunlight to form chlorophyll, and the whole leaves will turn yellow and then fall off, and this disease can be avoided by supplementing light.

Fourth, fat yellow. The yellowing of flowers caused by excessive fertilization or excessive concentration is manifested in dry brown at the top of the new leaves, and the general leaf surface is thick and dull, and the concave and convex are not stretched, and the old leaves are scorched and yellow. Fertilization should be stopped immediately, and part of the fertilizer should be washed with plenty of washing in severe cases.

Fifth, burn yellow. Strong sunlight directly onto some shade-loving flowers (such as spider plants, hostas, etc.) is easy to cause the leaf tips and leaf margins of flowers to wither, and the sunny part of the leaves to appear yellow spots. Move to the pubic area.

Sixth, water yellow. The young leaves are dark yellow and dull, the old leaves have no obvious changes, the branches are small yellow-green, and the new shoots are shrunk and not long, indicating excessive watering. Depot the flowers, put them in a ventilated and cool shade, and dry the soil ball before putting them back into the pot.

If the shallot is diseased, the germ will affect the health of the plant and will also cause the leaves to turn yellow. Common diseases include downy mildew, gray mold and purple spot disease, etc., after finding the disease, it is necessary to pull out the diseased plants in time, and use the corresponding drugs to irrigate the roots around to eliminate the residual bacteria. Ventilation should be strengthened in normal times, especially when the planting density is high.

It is possible to be malnourished, and when the leaves of the onion turn yellow, fertilization is needed to replenish the nutrients of the soil. Generally, nitrogen, phosphorus, potassium 1:1:

1. Compound fertilizer. Compound fertilizer is rich in nutrients, which can quickly supplement the nutrition of shallots and repair the yellowing of shallots. After applying the compound fertilizer, the fertilizer must be watered and dissolved to promote absorption.

Lack of light yellow long-term shade environment, the leaves do not get enough sunlight, can not form chlorophyll, the whole leaf turns yellow and then falls off, supplemental light can avoid this disease.

There are two common factors on green onions, one is thrips hazard, causing small white spots, scattered or dense irregular small white spots. One infection is white spots caused by gray mold, which are larger than those that are harmed by thrips.

Allium thrips are harmful, resulting in the appearance of small white spots. In general, thrips can be controlled with nicotinic insecticides, such as imidacloprid and acetamacim. or resveratine, picrisin, bifenthrin, spinosadin, ethyl spinosad, ear mold, spirome ethyl ester and other spray control.

Add silicone for even better results. If it is difficult to beat, it is recommended to use the drug: ethyl spinosad + chlorfenapyr + silicone penetrant (the cost is high, and it can be used when the benefit is good.)

The effect is good, at the same time, to control thrips, pay attention to the duration of the effect, and the number of days between sprays (no matter what insecticide you use to control thrips, remember to add silicone here, because the green onion leaves are slippery, if you don't add silicone together, the leaves will not stick to the leaves, and the effect will not be so good).

Onion gray mold, if it is a greenhouse, pay attention to control the humidity of the greenhouse, and reduce the humidity under proper ventilation to reduce the incidence rate. Prevention and control, iprodione + Pythium, or fludioxonil, or fludioxillium. Azoxymycline, or azoxymycline, or pyroxyxinazole, or pyraclostrobin fluazole amide and other drugs plus potassium dihydrogen phosphate spray for prevention and control.

The disease resistance situation is different in each place, so it is recommended to choose new ingredients that are not commonly used or used before, and use them alternately or choose two ingredients with different mechanisms to mix together. Apply the medicine once every 6-7 days, 2 times in a row.

The growth of diseased leaves of green onion is inhibited, the leaves are twisted and thinned, resulting in uneven leaf surface, the leaf tips are gradually yellowed, sometimes yellow-green mottled or yellow long spots of different lengths are produced, the onion tube is twisted, the growth is stagnant, the quality is reduced, the leaves droop and turn yellow, and the whole plant is dwarf or atrophied.

Onion yellow dwarf disease mostly starts at the seedling stage, the growth rate slows down or stops growing, the diseased plants are obviously dwarfed, the leaves are wavy or flattened, and yellow-green spots or yellow long spots appear on the leaves.

Reasons for the sharp yellow leaves of dried green onions:

1.The soil is too wet. Green onions are native to Central Asia, West Asia and other places, drought resistance, not too large wet fiber fiber filial piety.

Especially in the slow growth stage of high temperature, drought will not cause death, and excessive soil moisture often causes waterlogging and death of plants, which is the saying "green onions do not die and drown". This year, the summer and autumn rains are more frequent, although the rainfall is not large, but the soil has been in a moist state, causing waterlogging, suffocating the root system, and the aboveground part of the leaf yellowing.

2.The air humidity is too high. There is a layer of wax on the surface of green onion leaves, which has the effect of protecting water dispersion and loss, and the transpiration effect is small.

This year's summer and autumn have more cloudy and rainy days, and the air humidity is high, which inhibits transpiration. As a result, the absorption of the root system is reduced, and the nutrients brought to the leaves by absorbing water - nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, zinc and other fertilizer elements - are also greatly reduced. Long-term lack of fertilizer elements can also cause yellowing of leaves.

3.The disease is severe. Due to years of continuous cropping, soil-borne diseases are serious, resulting in a large number of soft rot, blight, root rot and downy mildew. In addition, excessive soil moisture exacerbates the damage of diseases, which can cause dry and yellow leaves.

Measures to prevent dried green onions from yellow leaves:

1.Deep ploughing and drainage, timely drainage. Generally, it is required to plough 30 cm.

When there is no deep tillage condition, the soil conditioner can be applied with water at the time of planting, or in August and September - no deep tillage, 200 grams per mu, about 20 days, can make the soil 50 100 cm deep loose and permeable. The soil is loose, the general small and medium-sized rainwater seeps down, the surface does not accumulate water, prevents waterlogging, and reduces the humidity; The root system is well developed, the plant is robust, the resistance to erection is strong, and the waterlogging damage is also reduced.

2.Top dressing outside the roots. 8 In September, combined with the prevention and control of pests and diseases, spray a nutrient solution every 10 days - 2 thousandths of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, zinc and other fertilizer elements to prevent the lack of nutrients.

3.Spraying the plant growth regulator - natural brassinin Shuofeng 481 every 10 20 days can promote photosynthesis, improve nutrient production, improve disease resistance, and reduce yellow leaf phenomenon.