In the process of planting watermelon, I believe that most melon farmers are most afraid of watermelon diseases and insect pests, in the growth and development of watermelon, in order to develop healthily, in addition to scientific planting technology, but also inseparable from the timely prevention and control of diseases and insect pests. Once the outbreak of diseases and insect pests in the melon field, if it is not prevented in time, it will often cause great harm to the growth and development of watermelon, and will cause great losses to melon farmers, so the prevention and control of diseases and insect pests is the top priority.
It is now the end of March, and it is about to enter April, which is also the period of watermelon budding and leaf spreading, when the health of watermelon plants has a great impact on future growth and yield. And from late March to early April, it is very easy to occur infestation of fly pests in the gray ground, this pest specifically endangers the seedlings of watermelon, once it breaks out, the harm can be imagined, so how to prevent the outbreak of fly pests in the gray ground of watermelon?
For the control of grayfield flies, melon farmers can start from the following four aspects:
Familiar with the harmful characteristics of grayland fly species
Learn about the morphological characteristics of the greyland fly
Master the occurrence of gray ground fly breeding
Learn scientific prevention and control techniques and take timely measures
<h1 class="pgc-h-arrow-right" >: What are the hazard characteristics of grayland fly breeding? </h1>
The grey ground fly belongs to the insect class, diptera, flower fly family, which is also known as the melon seed fly, melon farmers commonly call it maggots, seed flies, root flies, vegetable maggots, root maggots, etc., is an important pest of watermelon. When harming watermelons, gray ground flys harm the roots and stems of watermelon seedlings in the form of larvae, which is very easy to cause the death of watermelon seedlings. When the watermelon plant is damaged, the plant part on the ground will have symptoms similar to water loss, resulting in the plant being dwarfed. When the root system of the affected plant is dug up, the larvae of the gray ground fly can be clearly seen nibbling on the roots of the affected plant, resulting in the rhizome rotting or even dying of the plant. In addition, the wounds left by the gray ground fly in the invasion of watermelon plants are also very easy to be infected by pathogens, resulting in invasive diseases on the plants and secondary injuries.
Larvae in the soil harm the roots of watermelons
< h1 class = "pgc-h-arrow-right" > second, the morphological characteristics of grayland fly species</h1>
1. Morphological characteristics of adult insects
The adult body length of the grayland fly is about 4 to 6 mm, and the female adult is quite different from the male adult, and the male adult is slightly smaller than the female adult. The male adult has a dark yellow body, a head with black antennae, two compound eyes that look very connected, three black stripes on the back of the chest, and a pair of insect wings. There is also a black stripe on the back of the abdomen, and a black stripe on each abdominal segment.
Grey ground fly male adults
Female adults have yellow bodies, and unlike the apparent black stripes on the abdominal back of male adults, the stripes on the female adults' abdomen are not obvious.
Head characteristics of female adults
2. Morphological characteristics of pupae
The chrysalis is yellowish-brown oval in shape and about 5 mm long, and 7 pairs of protrusions can be clearly seen in the tail of the pupae.
The internal morphology of pupae and pupae of greyland flies
3. Morphological characteristics of the larvae
The larvae of the greyland fly are about 8 mm long, the hatching larvae and the middle-aged larvae are transparent white, the mature larvae are yellowish milky white, the head of the larvae has degenerated, only a pair of black mouth hooks can be seen, the whole body is thin and thick, and there are seven pairs of undivided protrusions at the end of the abdomen, it is worth mentioning that the seventh pair of protrusions is very small, and because it is born in the middle of the sixth pair of protrusions, it is often not visible when looking at the larvae from above.
Grey ground flies are old and mature larvae
4. Morphological characteristics of the egg
The eggs are milky white oval in shape, about 1 mm long, with slightly curved eggs and a reticulated surface.
<h1 class = "pgc-h-arrow-right" > third, the occurrence of gray ground fly occurrence</h1>
1. The growth law of gray ground fly
Greyland fly can occur multiple generations a year, and the algebra of different regions is also different, generally in the northeast region can occur 2 to 3 generations per year, while in the northwest region can occur 3 to 4 generations per year, in Shaanxi region will occur 4 generations per year, and in central China can occur up to 5 to 6 generations per year. It is worth mentioning that the growth and development rate of the gray ground fly is greatly affected by the temperature, when the average temperature is 17 °C, the development time of the gray ground fly to complete the generation is about 40 days; and when the average temperature is 25 °C, the development time of the gray ground fly to complete the generation is about 20 days; and in the spring, when the average temperature is 17 °C, the development time of the complete generation is also about 40 days, but when the average temperature in autumn is 12 °C, the time to complete the development of the generation takes 50 to 60 days. The gray ground fly in the north and south also has a big difference in wintering, the gray ground fly in the north overwinters in the soil in the form of pupae, while the gray ground fly in the south will have various forms in winter.
2. Occurrence habits of greyfield fly species
In March and April of each year, the adult gray ground fly begins to feather and lay eggs, and in late April, the first generation of larvae begin to occur, which lasts until early May, it is worth mentioning that the northern spring feathered adults will first feed on the manure in the field and on the flowering plants, and the eggs will be laid in the moist soil layer, and very close to the roots of the plant, when the eggs hatch, the larvae will begin to harm the plant's young shoots and roots, resulting in severe lack of seedlings.
3. The life habits of grayland fly breeding
The eggs, larvae and pupae of the greyland fly live in the soil, while the moist soil is very beneficial for its development and reproduction, and if the soil of the melon field is overly moist, the insect infestation will be more serious. The adults of the grayland fly are very active in the sunny afternoon, and especially like the rotten taste, especially the unripe manure in the melon field and the fermented cake fertilizer have a very strong tendency, and these two fertilizers can cause the adult insects of the grayland fly to cluster and lay eggs. It should be noted that when the temperature is above 35 ° C, about 70% of the eggs will not be able to hatch, and the larvae and pupae will also die due to high temperatures, so it is rare to see gray ground flies in the hot summer. It is worth mentioning that the gray ground species fly is very fond of coming out during the day and will lie still in the shade at night, while its larvae mostly move under the surface soil and in the young stems of the plant.
<h1 class = "pgc-h-arrow-right" >4. How to scientifically control grayland flies? </h1>
The control of grayland flies mainly starts from three aspects: agricultural control, physical control and chemical control. The specific prevention and control methods are as follows:
1. Agricultural control
As mentioned earlier, the gray ground fly has a strong tendency to uncorried manure, therefore, for the watermelon planted in the greenhouse, when fertilizing, we must pay attention to avoid applying uncorried manure, to apply fully decomposed organic fertilizer, and in order to reduce the spawning of gray ground fly, melon farmers should pay attention to the uniform application of fertilizer when fertilizing, and to apply deeply, especially note that seeds and fertilizer should be separated, and can also be covered with a layer of poisonous soil or add a certain dose of agent to the fertilizer. This can effectively reduce the harm caused by the spawning of gray ground fly. For the greenhouses that have already occurred, we should pay attention to frequent watering, and even water when necessary, it is necessary to pay attention to the fact that it is best not to irrigate when the watermelon squats.
In addition, do not apply manure water when topdressing, you can use fertilizer to replace manure water, which can effectively reduce the harm caused by pests. For open-field watermelons, it is necessary to pay attention to ploughing the ground after entering the autumn, so as to kill some of the pupae after wintering. If the cultivation site has already occurred insect infestation, it is also necessary to water frequently or even water heavily, and it is also not suitable for irrigation when squatting seedlings.
2. Physical prevention and control
During the occurrence of adult flies in the gray field, insect trap boards can be set up in greenhouses or melon fields to trap adult insects, so as to reduce the number of pests and reduce the harm.
Worm trap plates
3. Chemical control
Chemical control is generally only for the adult insects of gray ground fly spray control, especially in the adult season to timely spray control, but melon farmers should pay attention to avoid the use of organophosphorus pesticides as much as possible to prevent watermelon drug damage.
Commonly used effective agents are: 2.5% cypermethrin emulsion 3000 times liquid, 90% dimethoate crystal 800 times liquid, 20% killing emulsion 6000 times liquid, etc., and if the larvae are found on the root system of watermelon, you can use 5% natural pyrethroid emulsion 1500 times liquid for root irrigation, you can also use 1.8% avermectin emulsion 2000 times liquid to replace.
For the watermelon cultivated in the facility, melon farmers should pay attention to the feathering period of the adult flies in the gray ground in March, at this time, the sweet and sour attractants can be placed in the shed to attract the flies, generally 3 to 5 small plates can be placed in each shed with sweet and sour inducers.
Summary: The harm of gray land flies to watermelons is very large, and now it is in March, not only is the growth of watermelon an important period, but also the feathering period and spawning period of gray ground fly adults, then melon farmers should pay attention to timely control of gray ground flies, to avoid the outbreak of insect pests, and want to prevent the outbreak of gray ground fly infestations in time, you must have enough understanding of its habits, and learn scientific control technology, so as to be able to prescribe the right medicine and avoid missing the best time to prevent insects.