How to prevent and control taro fusarium wilt? These methods you need to know

Taro is a fairly common ingredient in our daily life, and steamed pork ribs with taro is one of my favorite dishes. I remember that the pond edge in my hometown was planted all around with taro, and by the time of the Mid-Autumn Festival, the grandparents of the older generation there had the habit of eating taro.

What is taro

Taro, also known as yu or yunai, is the underground corm of a plant in the Araceae family. Its shape and flesh vary by variety, and the kind usually eaten is the small taro. It is a perennial tuberous plant, often cultivated as an annual crop. The leaves are shield-shaped, and the leaf stalks are long and thick, green or purplish red; the base of the plant forms a shortened stem that gradually accumulates nutrients and enlarges into a fleshy corm, called "taro" or "mother taro", which may be spherical, ovate, elliptical or block-shaped. Each node of the mother taro has a bud, but the axillary buds at the middle and lower nodes are the most active, producing the first tiller and forming a small corm called a "daughter taro", from which "granddaughter taros" then arise, and under suitable conditions great-granddaughter or great-great-granddaughter taros and so on can form.

Growth habits of taro

Taro likes high temperatures and moisture, is not drought-tolerant, is relatively shade-tolerant, and has the characteristics of an aquatic plant, so it can be cultivated in either paddy fields or dry land. Its root system has weak absorption capacity, and the whole growth period requires sufficient water; it has broad adaptability to soil, with fertile, deep, clayey soil with strong water retention being preferable; seed taros begin to sprout at 13-15°C, the optimum temperature for growth is above 20°C, the corm forms under short-day conditions, and the optimum temperature for development is 27-30°C. If it encounters low temperatures and drought, growth is poor and yield is seriously affected.

Taro is rich in nutrients, containing large amounts of starch, minerals and vitamins. It is both a vegetable and a food grain, and can be eaten cooked, dried or made into flour. Because taro starch granules are small, only one tenth the size of potato starch, its digestibility can reach 98.8%, and in taro processing it can be made into taro flour and taro paste filling to extend storage.

There are about 100 or more different kinds of taro; some are elliptical like sweet potato, while most others are round. Compared with other tuberous plants, taro has fewer strange shapes. Taro can grow to 6 feet tall and has broad leaves; however, the young shoots can be eaten after being blanched in boiling water. The leaves and young shoots are less used in Western markets. The tuber part is dark brown, and the outer skin is ringed and quite rough, with hairs on it. The flesh may be white, off-white or purplish gray, and some has pink or brown streaks.

How to prevent and control taro fusarium wilt

1. Symptoms of taro fusarium wilt damage:

Taro fusarium wilt, also called dry rot, is one of the common and important diseases in taro-producing areas. It mainly parasitizes the stem, causing wilting or rotting. In mild cases the symptoms are not obvious, and old leaves yellow rapidly. Severely affected plants show poor growth, turn yellow-green, dry up early in autumn or have stems and leaves lodging; when the corm is peeled open, the cortical layer turns red, and in severe cases large sections turn reddish brown, causing dry rot or hollowing.

2. Occurrence pattern of taro fusarium wilt:

It mostly occurs in summer and autumn. It is prone to occur when the temperature is 28-30°C. Continuous cropping cultivation. Many underground pests easily induce this disease. Extensive management, or soil that is too dry or too wet, leads to severe disease.

3. Prevention and control methods for taro fusarium wilt:

① Seed disinfection. When necessary, seed taros can be soaked in a 500-fold dilution of 50% carbendazim wettable powder for 30 minutes, then dried and sown directly.

② Agricultural control. Keep seed from disease-free land or disease-free plants, and select disease-free seed taros, preferably granddaughter taros or daughter taros, and use mother taros as little as possible. Implement crop rotation of more than 3 years, and after harvest promptly remove diseased residues, carry them out of the field and bury them deeply or burn them. Adopt high-bed or ridged cultivation, and in the south spread rice straw or wheat straw on the bed surface to lower soil temperature.

Cultivation and management of taro  

1. Land preparation and ditching. After the land is prepared, open ditches at a row spacing of 80-100 cm, with a ditch width of 50 cm and a ditch depth of 35 cm, then apply fertilizer in the ditches.  

2. Fertilization. Taro has a high fertilizer requirement and a long growth period, so first apply sufficient base fertilizer: 2000 kg of high-quality organic fertilizer per mu, and 60 kg of 48% potassium sulfate compound fertilizer (16-16-16), applied in ditches according to row spacing. Topdressing should be applied in several split applications, 2-3 times in total during the seedling stage, the vigorous growth stage and the corm growth peak stage, mainly with phosphorus and potassium fertilizers.  

3. Sowing. The sowing time is after Qingming (that is, early April), with a plant spacing of about 50 cm, the seed 3-5 cm from the ground surface, and 5 cm of soil covering. Plastic film mulching cultivation can also be used.  

4. Watering. Taro is averse to dry soil; when drought occurs, leaves turn yellow and wither, but soil that is too wet and waterlogged is also unfavorable for root growth. During the seedling stage, the soil should have sufficient bottom moisture, and watering should be avoided. During the seedling stage, keep the soil alternately dry and wet, and pay attention to drainage when it rains.  

5. Intertillage and hilling. During the seedling stage, combine topdressing with intertillage to remove weeds and warm the soil; at the end of the seedling stage, cultivate and make the cultivation ditch level with the ground. After that, hill up once about every 20 days, 7 cm thick, for a total of two times. The purpose of hilling is to inhibit the sprouting and growth of the terminal buds of daughter taros and granddaughter taros, reduce nutrient consumption, allow the taro to fully expand and produce a large number of adventitious roots, and increase drought resistance. As the farming proverb says: "If you don't hill taro, it's as good as not planting it." Along with hilling, according to the distribution density of leaf area and the season, remove excess side buds as early as possible, so as not to consume nutrients and restrict the growth of daughter taros. 

The main thing in growing taro is preventing its fusarium wilt. Fusarium wilt mainly occurs in the stem of taro, and if it is not treated and prevented in time, it will cause a decline in taro yield, and in severe cases it will also lead to drying up or lodging of stems and leaves. Therefore, no matter which crop is grown, disease prevention is very important.