After a long time of planting, some lawns will turn green late in early spring and turn yellow. Some plots may even degenerate and die, affecting the ornamental effect. Identification method The distribution of physiological yellowing in the field is generally
After a long time of planting, some lawns will turn green late in early spring and turn yellow. Some plots may even degenerate and die, affecting the ornamental effect.
Identification method
Physiological yellowing is generally distributed in patches in the field, but sometimes it occurs locally. Physiological yellowing is not contagious and can be diagnosed through inoculation tests. No pathogens can be seen in the yellowed parts, and the color is uniform.
Causes and prevention
Lack of nutrients
During the two peak growth periods of cold-season lawns in spring and autumn, due to the dry climate in the north, little rain, and weak soil leaching, base ions are easily retained in the soil in large quantities, and soluble alkali metal carbonates are also present in the soil, and fertilizers are often lacking. The cause of lawn yellowing, especially the yellowing caused by iron deficiency, deserves attention. The prevention and control methods are as follows:
Strengthen maintenance and management, regularly apply single-element fertilizers or multi-element compound fertilizers, and immediately water thoroughly after fertilization so that the fertilizer can penetrate into the root system and be fully absorbed by the root system to prevent yellowing caused by lack of nutrients.
For lawns showing symptoms of deficiency, fast-acting fertilizers can be applied to the leaves according to the symptoms of deficiency to improve the quality of the lawn, but the concentration should not be too high
Insufficient light
Due to improper management measures, the lawn grass grows too high, resulting in poor ventilation and light transmission in the lower part. After mowing, the yellowing of the local lawn due to insufficient light can be avoided by strengthening management. The prevention and control methods are as follows:
Regularly comb the lawn, clean the covering material under the lawn, and improve its growth environment.
The climate is suitable in spring and autumn, and the lawn grass grows vigorously. In order to maintain the height of the lawn, the mowing frequency is once a week, and the stubble height can be adjusted according to different grass species. Generally, the annual grass is 3 to 4 cm, the tall fescue is 5 to 6 cm, the bentgrass is 1 to 2 cm, and the ryegrass is 3 to 4 cm.
During the hot summer, the cool-season lawn has dormant characteristics. During this period, the lawn grows slowly, the number of mowings should be relatively reduced, and the mowing frequency should be once every 2 to 3 weeks. The stubble height should be relatively increased to enhance the resistance of the lawn grass to adverse environments.
High temperature, drought, and little rain
High temperature, drought, and little rain are the climate characteristics of North China in recent years. The cool-season grass that likes fertilizer and water has enhanced transpiration and accelerated water evaporation due to high temperature. If water is not replenished in time, it is easy to form yellowing caused by drought, affecting the beauty of the lawn. The prevention and control methods are as follows:
Timely irrigation. After rainfall, water enters the soil. After transpiration from the lawn leaves, evaporation from the surface, and water seepage into the ground, the water required for lawn growth will be seriously insufficient in dry weather, resulting in yellowing or even death of the lawn. Timely irrigation is necessary to ensure the water demand of the lawn root system. Irrigation is the prerequisite for normal lawn growth. In the hot summer, irrigation can adjust the microclimate, reduce the temperature, prevent burns, and enhance the competition between the lawn and weeds.
The method to determine the time of lawn irrigation is to check the soil with a knife or soil drill. If the soil at the lower limit of the root distribution of 10 to 15 cm is dry, it should be watered. Sprinkler irrigation is more uniform. Since the lawn roots are mainly distributed in the soil layer above 15 cm deep, it is advisable to moisten the soil layer to 10 to 15 cm after each irrigation.
Frozen water should be poured before winter comes, and green water should be poured in early spring to make the lawn turn green early.
Combing the dead grass layer,The dead grass covering layer hinders the ventilation and absorption of sunlight of the lawn grass, affects photosynthesis, and provides a place for the reproduction and overwintering of pathogenic bacteria spores and pests, leading to the occurrence of diseases and pests. Combing can be done once in early spring and late autumn. Using a grass comber or hand rake to remove dead grass is conducive to the timely greening of the lawn and the restoration of green.
Applying urea In addition to water, air and sunlight, the growth of the lawn also requires sufficient nutrient supply. Reasonable fertilization can provide the required nutrients for lawn plants. Quick-acting nitrogen fertilizer can stimulate the growth of stems and leaves of lawn plants and increase green. Urea has the highest nitrogen content in fertilizers. In the past, urea was used for manual application before the rainy season. Practice has shown that this method causes uneven yellow-green color of the lawn and is easy to be infected with diseases. This year, the urea is melted with warm water from the fountain first, and then sprayed with a water truck, which has a better effect.
In addition to nitrogen fertilizer, phosphorus and potassium fertilizers should also be applied to improve the resistance of the lawn. The time for fertilization is early spring, summer and autumn. Nitrogen fertilizer is applied in early spring and late autumn, and phosphorus fertilizer is applied in summer.
Lawn aeration　
Lawns that have grown for many years have their surface compacted due to rolling, watering, and trampling. At the same time, due to the accumulation of dead grass layers, the lawn grass is seriously lacking in oxygen, its vitality decreases, and the lawn turns yellow. Aeration is a form of lawn aeration.
Soil aeration can increase soil permeability, facilitate the entry of water and fertilizer, reduce soil compaction, stimulate the growth of lawn roots, and control the appearance of dead grass layers. Aeration should not be performed when the soil is too dry or too wet. Aeration in hot and dry weather can cause root drying. The best time to aerate is when the lawn is growing vigorously, has strong resilience, and is in good environmental conditions. Irrigation must be carried out after lawn aeration, and fertilizer should also be applied.
Post time: Oct-14-2024