Sunflowers belong to the Asteraceae family and are also known as sunflowers. Its seeds are not only important oil crops, but also can be fried and eaten, so they have high economic value. In recent years, with the continuous expansion of sunflower planting area, in order to improve the efficiency of planting, it is extremely important to seriously do a good job in pest prevention and control. Based on this, this paper first analyzes the common pests and diseases of sunflowers and their control countermeasures, and then discusses the meteorological conditions for the occurrence of sunflower diseases and insect pests.
In the process of sunflower growth, due to the influence of meteorological conditions, it is easy to cause a series of diseases and insect pests, which seriously affects the yield and quality, so it is of great practical significance to do a good job in pest control from meteorological conditions.
Common sunflower pests include ground tigers, sunflower borers, scarab beetles and golden needle worms. For underground pests, the use of oxidized fruit to prepare poisonous bait can play a good control effect. Insect pests such as scarab beetles can be prevented by spraying sodium fluorosilate because they can harm the stems and leaves of sunflowers.
Common sunflower diseases mainly include sclerotia, rust and lidang. For rust, in order to reduce the incidence of disease, growers should do a good job of seed selection, adhere to crop rotation, and apply an appropriate amount of potassium fertilizer to reduce the incidence. For sclerotia, due to the serious damage to the stems and discs of sunflowers, it can be controlled by "Redowella" seed mixing. For Ledang, because it parasitizes the roots of sunflowers, it will absorb a large amount of sap, affecting the growth of sunflowers, so growers should eradicate them in time.
1.3.1 Sunflower sclerotia
Once sunflowers are infected with sclerotia, there will be serious symptoms, flower disc rot, seed kernel rot, resulting in sunflower death and extinction, especially infection with root rot, flower rot type sclerotia, the most harmful. For the prevention and treatment of the disease, in the early stage of sunflower dishing, sclerotium net or carbendazim can be used to prevent and control by spraying, focusing on the protection of the back of the flower plate. It should be pointed out here that due to the large size of the sunflower plant, the spraying is more difficult, so it is best to go to the field after the rain to play a rod to reduce moisture.
1.3.2 Sunflower brown spot disease
In order to reduce the incidence of brown spot disease, growers should conscientiously do a good job in cultivation management, reasonably control the sowing density, timely weeding and fertilization, and improve their disease resistance. In long-term rainy weather, if it is found that there is water accumulation in the field, the drainage work should be done in time, and the pages of early onset should be removed in time. Or carbendazim and other drugs can be used for prevention and control, and the flower disc and the middle and lower leaves should be sprayed at the same time, which can play a good control effect.
1.3.3 Sunflower borer
Sunflower borer is an important pest that harms sunflowers, especially in July-August, a large number of adult sunflower borers feed on sunflowers and lay eggs around 8 o'clock at night, and in early August the eggs become larvae, eat sunflower seeds, and spit silk knots. If you face rainy weather at this time, it will lead to serious rot in the flower tray, affecting its yield and quality. For the control of this insect pest, it is possible to spray the enemy insects, the effect is good, but it should be pointed out that the drug will harm the bees, resulting in the sunflower empty shell, so it should be used with caution. Alternatively, 2 l of endosulfan emulsion + 400 l of water can be used, and spraying flower pots can also play a good control effect.
During the entire growth process of sunflowers, due to the influence of many factors such as temperature and humidity, light and wind, their growth will be affected, increasing the incidence of diseases and insect pests. The occurrence and epidemic of sunflower diseases and insect pests often need to follow the following conditions: (1) the host of diseases and insect pests; (2) the development of diseases and insect pests is in a harmful period; (3) the conditions for the survival and development of diseases and insect pests. Under the influence of these three factors, sunflowers and surrounding plants, soil will become an important host, its survival and development conditions are combined with meteorological conditions to judge, if the meteorological conditions meet the growth requirements of pests and diseases, it will lead to rapid reproduction of pests and diseases, seriously affecting sunflower yield and quality, serious will lead to extinction.
The prevalence of sunflower pests and diseases is based on temperature, and its temperature range is between 6 °C and 36 °C, and there will be some differences in the prevalence of pests and diseases. Taking sunflower borer as an example, the most suitable temperature for egg hatching is 18 °C-32 °C, especially when the temperature exceeds 26 °C, the hatching rate is the highest. Within the right temperature range, the frequency of pest and disease development is significantly accelerated, and as the number of pests continues to increase, the harm is greater.
In different humidity conditions, the tolerance of pests and diseases is also different, some pests prefer humid environments, and some prefer dry environments. If the humidity conditions meet the growth and reproduction needs of sunflower diseases and insect pests, they will multiply in large quantities in a short period of time, seriously affecting their growth.
The constant change of wind speed is an important factor affecting the spawning and migration of sunflower diseases and insect pests. In general, the size of the wind will produce different stress changes, weak winds, will affect the flight of pests, for pests that do not have strong wind resistance, weak winds will also affect their freedom. Especially in strong windy weather conditions, it will have a great impact on the speed and direction of the pest.
The influence of light on sunflower diseases and insect pests is mainly determined by three factors, including light waves, light intensity and photoperiod. Among them, light waves will affect the phototropism of pests and diseases, while light intensity will affect their range of activities and rhythms, including habitat, spawning and mating, etc., and the photoperiod will affect the diapause and dormancy of sunflower pests.
In summary, as an important oil crop and cash crop in China, sunflowers will seriously affect their yield and quality once infected with diseases and insect pests. Meteorological conditions as an important cause of diseases and insect pests, so we must pay enough attention to it, starting from meteorological conditions and other factors, conscientiously do a good job in the prevention and control of diseases and insect pests, and specifically take the above aspects of the prevention and control countermeasures, so as to better protect the yield and quality of sunflowers, improve planting efficiency, promote the healthy development of sunflower planting industry, and promote regional economic development.