Drug farmers should pay attention to tuber rot in the late growth stage of Pinellia ternata

Cause of disease

Pinellia ternata grows from August to October, that is, it enters the mildew and rainy season. The second, third and fourth generations of bulbs formed by Pinellia ternata planted in early spring and the first and second generations of Pinellia ternata cultivated in summer expand rapidly and form tubers. The small mother stem planted during cultivation is also expanding itself. This period is the fastest growing stage of Pinellia ternata tuber, and it is also the weakest period of Pinellia ternata tuber resistance to external infection. the larger the tuber is, the weaker the resistance is, the smaller the tuber is and the stronger the bulb defense ability is. The rapid growth of underground Pinellia ternata tubers needs to absorb a large amount of oxygen and organic matter in the soil, and during this period, the microorganisms in the soil are also very active, reproduce the fastest, and need a lot of oxygen. And discharge a variety of harmful gases and substances at the same time. During this period, when there is continuous rain, high soil humidity or soil consolidation, and when the gas in the soil and the air cannot be exchanged in time, the tuber of Pinellia ternata is in a period of rapid expansion, because the protective layer of the outer skin has a weak ability to resist infection. A large number of harmful gases and bacteria in the soil will easily invade the tuber of Pinellia ternata and spread rapidly, causing the tuber of Pinellia ternata to rot in a short time, and 80% of the light ones rot in a week, resulting in heavy plots. After 3-5 days, all the tubers of Pinellia ternata rotted away, and the soil and air of the whole plot smelled fishy. As a result, Pinellia ternata was completely destroyed, and the hard planting and management of Pinellia ternata could only harvest some beads and some small tubers, which caused serious losses to the production of Pinellia ternata. This rot is one of the main bottlenecks restricting the production of Pinellia ternata.

Symptomatic features

At the initial stage of pathogen infecting Pinellia ternata tuber, irregular black spots appeared around the tuber, which expanded rapidly in all directions. 3-4 days later, many bacterial spots joined together and continued to infect the tuber. At this time, the root system of Pinellia ternata began to atrophy, and the aboveground leaves gradually changed from green to yellow and withered. A week later, the tuber of Pinellia ternata showed a round blister, like a ripe grape, the tuber was full of black water, and the whole plant died, leaving only a thin skin. The spread of bacteria will quickly infect other Pinellia ternata tubers, causing the whole Pinellia ternata to rot in a short period of time, and the soil and air of cultivated Pinellia ternata give off a fishy smell.

Prevention and cure method

Select varieties: to plant Pinellia ternata, we should choose Pinellia ternata varieties with strong disease resistance and vigorous growth, such as "narrow clover", "willow leaf shape" and so on, and select disease-free tubers or bulbs as seed stems.

Seed stem treatment: before sowing, the selected seed stem must be treated and disinfected, such as drying seeds and chemical dressing, to prevent the seed stem itself from carrying germs.

Land selection: a plot of loam or sandy loam with a PH value of 6.5 to 7 must be selected to plant Pinellia ternata, and there has been no root rot or rot in this plot before. In rainy areas in autumn, the selected plots should have a slope of 20%. For plain areas and flatter plots, every other interplanting bed should be left with a drainage ditch of 30 cm wide and 30 cm deep when planning for the early stage of cultivation of Pinellia ternata. To ensure that in case of continuous rainy weather, the water in the soil of the Pinellia ternata can thoroughly infiltrate into the drainage ditch and discharge the plot in time.

Remedial measures: in case of continuous rainy weather and moist soil, as long as ploughing in the field can be carried out, various forms of ploughing and loosening the soil should be carried out for many times, so as to break the soil lamination, remove harmful gases from the soil and enter the fresh oxygen in the air, and increase the gas exchange between the soil and the air. This measure can effectively prevent and reduce the occurrence of rot.

Rush harvest of rotten stems: in the middle and later stages of Pinellia ternata growth, if you encounter continuous rainy weather and large soil moisture, you should frequently check the growth of Pinellia ternata, and if some Pinellia ternata plants are found to have rotten disease, in this case, no matter whether or not to planing and harvesting season, should be harvested in time, without delay, otherwise, the tubers rot very quickly, the ones that rot big first, then those that rot small, resulting in reduced production or even no yield. At the same time of emergency harvest, the tubers of Pinellia ternata harvested from the wet mud should be peeled and processed immediately, so the interior of the fresh tubers is still rotting, if not processed, most of the tubers will rot after 1 or 2 days.