Control of Frost injury of seed Sweet Potato

Sweet potato freeze injury, also known as hard heart potato.

(disease diagnosis) when the potato was frozen, the skin color of the potato was not significantly different from that of the healthy potato, but only slightly lost its luster. In the later stage, it can be seen that the potato skin is slightly dark and dull, and there is an elastic feeling by gently pressing the frozen part with your fingers. when you cut open the frozen potato, you can see that the potato meat close to the potato skin quickly turns brown, does not ooze white pulp, and exudates clear water by hand. Generally, according to the speed of browning of potato meat, we can speculate the degree of freezing. The faster the browning rate, the more serious the freezing. Frostbitten potato cubes often form a hard heart, bitter and can't be boiled. After the potato pieces are frozen, it is easy to cause weak parasitic bacteria and cause rot.

When the low temperature of potato is below 9 ℃ for a long time, the physiological function of potato will be damaged, the meat tissue will be frostbitten, and hard nucleus, epidermis and tissue necrosis will be formed. But after freezing, it takes a while before it begins to rot. The lower the temperature, the more serious the freezing injury. The longer the duration of low temperature, the more serious the freezing injury. Generally speaking, there are two peaks when potato pieces are damaged by freezing: one is that the production is harvested too late, and it is frozen in the field, which is called out-of-cellar freezing injury, which begins to rot about 15 days after entering the cellar; the other is in the middle and later stage of cellar storage. freezing damage occurs due to shallow pit or poor cold insulation and low pit temperature, and then rot. It usually begins to rot for half a month at 4: 5 ℃ and 1 month at 6: 7 ℃.

(control measures) (1) timely harvest, into the cellar to prevent potato pieces from freezing. The suitable harvest time of sweet potato should be controlled when the local ten-day average temperature drops to about 14-15 ℃. Harvest in time on a sunny day, and the potatoes should be harvested in the cellar on the same day. (2) disinfect the cellar, before the potato pieces enter the cellar, the cellar wall of the old cellar should be shoveled off a layer of soil, and then disinfected with chemicals, fumigating with 402 water agent 30ml per cubic meter, or spraying around the cellar wall with 50 times formalin, should be closed for two days and then opened for ventilation, and then used two days later. (3) selected potato pieces, those with disease, insect bite, frost and frozen potato pieces should be removed and cannot be entered the cellar. (4) in the process of harvest, transportation and cellar storage, it should be operated carefully and handled gently to prevent wounds as far as possible. (5) manage the temperature and humidity of the cellar well. Prevent potato pieces from freezing, safe storage, pit temperature at 11-13 ℃, relative humidity 75%-80%.