The cause of death of cabbage seedlings and even more Mature plants can be very different: it is bad care, pests and diseases.
Cabbage killed by pests
The most dangerous enemies the young seedlings of cabbage are cruciferous flea beetles. These are small jumping insects that just a couple of days can destroy fragile plant. They attack the tender leaves are planted in the garden of seedling and first turn in the sieve edges of cabbage leaves, and then the whole thing. If time does not take action, the sprouts will die.
To deal with the cruciferous flea beetle can be by different methods: chemical and folk. To people's concerns pollination of tobacco dust, ash, a mixture of ash and pepper, and so on. Can water and spray decoctions of tomato leaves, infusion leaves, garlic, dandelion root. It all is effective and safe in terms of healthy products from his garden, but after the first rain and even irrigation fleas attack again. Therefore, it is better to apply chemicals. Is pollination of dust and spraying of any drug from garden pests. For example, means "commander", "Intair", etc.
No less dangerous cabbage aphid. It appears on older plants, cabbage is not killed, but growth and formation of heads is slowed down, leading to lower yields. To deal with aphids on the sprouts can be soapy water, and chemicals.
Closer to the fall often die cabbage from cabbage moths. It is a brown butterfly, leading nocturnal. She lays on the leaves of cabbage eggs, which contain tracks, which are very voracious. If the heads are still small, the caterpillars can completely ruin them. To combat cabbage cutworms need a method of collecting pests and eggs manually from the leaves. But if the caterpillars have entered the heads, then you need to spray the plants with microbiological preparations. This "Dipel", "Lepidocide", etc. the Use of chemicals is undesirable, as the harvest typically is less than a month.
Cabbage killed by disease
"Black leg" - the scourge of seedlings, especially it occurs when crops are dense and waterlogged soil. The cabbage cernet and softens the stem, after which it can not keep the leaves and falls to the side. This is a very contagious disease, it literally decimated the crops of cabbage for a few hours. To deal with the "blackleg". Immediately remove all diseased specimens and destroy them, the seedlings to be put in a cold room, if possible. It is also recommended to throw dark pink solution of potassium permanganate. And not showering for a few days. Usually it stops further spread of the disease. To "black leg" did not appear again, decontaminate your soil for seedlings (proprivate steam or pour boiling water) and take it in the checked place, because the pathogen of this disease is long lived in the soil.
There is a disease of cabbage as kila. In seedlings it manifests itself as a thickening on the roots. If such a seedling is planted in the ground, eventually it will begin to wither. The leaves will turn yellow and then the sprouts will die. To treat her anymore, the fight against Clubroot is prevention. This soil treatment with chloride of lime after harvest, the mandatory rotation on the site and presowing treatment of seeds.
Cabbage killed by poor care
Cabbage likes moisture, but in reasonable quantities. If you pour the seedlings, most likely it will die because the roots simply rot. Also the cabbage you can't overdry, especially a few days after planting in the garden. She's afraid of sunlight, cover the planting with a thin acrylic. This is such a non-woven material, good pervious to light and air, and even moisture. By the way, the acrylic will help, and from cruciferous flea beetles. After the consolidation of the seedling shelter remove.