How can shrimp and crab farmers effectively prevent and control moss?

It's time to share the experience of farming with you again. I wonder if you have any small expectations? Today's sharing is a bit long, and it may be boring. Are you ready? )

In recent years, the prevention and control of moss has been a big headache for shrimp and crab farmers. In order to control moss, everything can be said to be done, but moss is still growing wildly. Seeing this business opportunity, some unscrupulous manufacturers abuse highly toxic drugs, killing only moss and not others, which has brought endless disasters to the majority of shrimp and crab farmers. 20 17 "killing mosses" case is the best example. In the final analysis, prevention is the key to the prevention of moss, and the sooner the better, the better to start from beginning of winter. The prevention and control measures of moss are nothing more than "fishing, killing, fattening and adjusting"

First, get to know Moss

Moss harmful to aquaculture belongs to filamentous algae. Aquatic plants, such as unbeaten, Juncus efflorescence and Nostoc flagelliforme, all survive by photosynthesis and compete with each other for sunlight, nutrients and turf in the same water body. Generally speaking, moss, unbeaten eating, running grass and so on. It's all about life and death. Once the moss closes the pond, unbeaten food, pitcher plants and other beneficial aquatic plants cannot survive at all. There is still a difference between the living state of moss and unbeaten eating and running plants. Generally speaking, the thinner the water quality, the greater the transparency, and the shallower the water, the more suitable for moss growth. Once the water becomes turbid, greasy and deep, moss is unlikely to survive. From another point of view, the presence or absence of moss is a sign of whether the water quality is polluted and the degree of pollution. If no measures are taken in the aquaculture pond, the moss will decrease, indicating that the water quality has changed. We must find out the reasons and take corresponding measures.

Second, why should we start to control mosses in beginning of winter?

Moss has appeared on the water surface that has been engaged in shrimp and crab farming for more than one year, so there are moss seeds in the pond. Throughout the winter and early spring after beginning of winter, Hubei is in a sunny and dry climate with low water temperature, which is not suitable for the growth of phytoplankton and algae. This kind of weather is extremely beneficial to the growth of moss. If it is not controlled, moss flooding in winter and spring will become the norm. For the newly dug shrimp and crab pond, if there is water at the bottom of the pond after early winter, moss will appear immediately and develop in a flooding trend.

There is a wrong idea that moss does not grow or even die in winter, so the prevention and control of moss in winter and spring is often ignored. In fact, in Hubei province, moss will not die in winter, but will only stagnate. Once the temperature rises in spring, it will quickly resume growth. Even if it dies, its resting spore will exist at the bottom of the pool for a long time, and once the environment is suitable, it will germinate and grow rapidly.

After winter, the moss has a certain concealment, and a small amount often sinks to the bottom of the water or adheres to aquatic plants. It is not easy to find it without careful inspection, but it has exploded when it is widely visible.

To sum up, the prevention and control of moss should start from the source, and the early winter after beginning of winter is the best time to prevent and control moss.

Third, effective means of moss control.

(1) Fishing:

Moss prevention and control begins with "fishing". There are four kinds of common mosses, some floating on the water, some sinking to the bottom, some adhering to aquatic plants, some lumpy, some lumpy, and the most troublesome is scattered in the water. Cloth moss is relatively easy to fish, and block moss is relatively better. The hardest thing to catch is the one that feels slippery. The tool for fishing slippery moss has a denser mesh, and it moves slowly when fishing from the bottom of the pool. Moss that has been covered with aquatic plants must be resolutely fished out, even if some aquatic plants are fished out, they will never be tolerated. No matter what kind of moss it is, when it just germinates, the amount of work picked up is the smallest, and it is also the most basic work that must be done first after beginning of winter. It is best to remove the picked moss from the culture area. If it is really difficult, spread it on the height of the pond embankment. After exposure for a period of time, remember to turn it over and then sun it, and then burn it after sun withering to avoid future troubles. Don't pile the removed moss at the water's edge to prevent it from spreading again!

(2) Kill:

Killing is the most effective and direct method to control moss. "Killing" methods can be divided into three types: sun killing, deepening water level and killing with drugs.

1, dry field killing

Throughout the winter and early spring, due to the sunny and dry climate in Hubei, the method of killing moss in dry fields is the simplest, economical and applicable. Whether it is a new pond or an old pond, the water in the pond must be drained, and a filter ditch should be dug in the pond with deep silt. Pay attention at ordinary times. Once there is water, drain it quickly. Never drain it. By exposing the bottom of the pool and frozen soil, most of the moss will be disposed of. When drying at the bottom, if there is massive moss, you must first dry it and turn it over before drying it, and then drag the dried moss away or burn it on the spot. This method is only suitable for ponds without shrimp seedlings and adults.

Step 2 deepen the water level

In winter and early spring, deepening the water level is beneficial to shading and is not conducive to the survival of moss at the bottom. When the water level is deeper than 1 m, because the transparency is difficult to reach more than 70 cm, it is difficult for the bottom layer to be illuminated, so the photosynthesis of the bottom layer moss is seriously hindered. Over time, the moss in the bottom layer and the moss in the deep water layer can't be illuminated, so they can't survive and kill the moss. This method is suitable for ponds with more young and adult shrimps.

3. Drug killing

In combination with pond cleaning, quicklime or tea cake can be added directly. Quicklime directly kills moss. Tea cake not only killed the wild fish in the pond, but also indirectly killed the moss through the subsequent fertilizer and water. High-quality moscide products on the market, combined with high content of sodium humate, can effectively kill all kinds of mosses directly. It is worth noting that on the pond slope above the water level, when the water level is low, it is necessary to mix the high-quality moss-killing products on the market with water and spray them once to kill these remaining moss spores. Otherwise, as the water level rises, these untreated places will breed moss once they encounter water, so they still have to be treated at that time, so it is better to prevent and control them in advance.

The combination of the above three methods is better.

(3) Fertilizer:

The principle of "fertilizer" method to control moss is to reduce the transparency of water by increasing the number of plankton. A large number of plankton living in the upper layer blocked a lot of light, which made the moss at the bottom unable to photosynthesis and died. This method requires a water depth of more than 70 cm, and the effect is better.

There is a misunderstanding that water and fertilizer cannot get up in winter. Of course, unless it is heavily polluted, it is necessary to maintain transparency below 30 cm in winter. I often see that the transparency of water around livestock farms is always less than 30 cm in winter, which is not what we advocate, but it is proved from another side that algae can survive and reproduce in winter. The transparency of crayfish ponds should not be too low (less than 40 cm). In winter and spring, it is possible to keep the transparency of crayfish pond at 50~60 cm as long as the method is proper.

In winter, it is very important to choose suitable fertilizer varieties. First, a proper amount of fermented organic fertilizer is used as the base fertilizer, and then the high-quality amino acid fertilizer on the market is combined with special fertilizer for shrimp and crab (mostly organic biological fertilizer) for spraying throughout the pond. Use once every 10~ 15 days can make the water transparent to about 50 cm, which not only effectively controls the moss, but also provides high-quality natural bait for crayfish.

(4) adjustment:

"Regulation" refers to measures such as detoxification, water diversion and decomposition of dead moss after the above three means. After a series of measures of "fishing", "killing" and "fattening", the water environment has changed greatly. Some water is turbid, some water is black, and some water stinks slightly after a large number of moss die. At this time, follow-up measures must keep up.

When the water is turbid, it can be treated with high-content sodium humate products and chemical flocculants. In other cases, organic acids or sodium thiosulfate products can be used for detoxification. If the water temperature is higher than 15, other follow-up problems can be solved with high-content Bacillus, compound Bacillus and lactic acid bacteria.

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