Growing Upland Taro: Part II
By Glenn I. Teves, County Extension Agent
In growing taro, water control is important. Using a timer is an efficient way to control water frequency and duration, and assures that surface roots are moist daily. Fertilizer and roots will only move where there is water. Clogging and pinching of the drip irrigation line is a major concern when growing taro, and some farmers will lay extra drip lines between the rows when there’s first indication of this problem. Insufficient water is the greatest stressor of taro, so some farmers are converting to new kinds of drip line that’s more rigid and less likely to pinch or clog.
Wind protection is important, but taro also needs good air circulation to deter diseases and pests. A major disease is leaf blight caused by a fungus called Phytophthora (‘leaf destroyer’) and is more prevalent at higher elevations than in the lowlands. This disease can melt the leaves and affect starch content and the sticky quality of poi. A week of cool wet weather creates ideal conditions for this disease, but increasing air circulation by planting farther apart during winter months can mitigate this problem. New hybrids developed by the University of Hawaii appear to be more tolerant to this disease. By crossing Hawaiian varieties with South Pacific and Asian varieties, hybrids have been created that are more vigorous and can overcome the disease quicker than the Hawaiian varieties. However, when conditions are ideal for the disease, it moves rapidly to affect all varieties, even the hybrids. Stories of ten feet tall plants with 20 pound taro throughout the state derived from these hybrids are not exaggerated. Still, the proof is in the poi, and it’s hard to beat a well grown Hawaiian wetland taro. However upland taro growers are coming close to producing tasty, sticky poi that’s difficult to distinguish from wetland poi.
Bringing the taro to harvest can be a challenge. Among the pests are aphids, ants and mealy bugs, root knot nematodes, and spider mites. The key to controlling most pests is to grow a healthy plant and not allow it to get stressed. For home gardeners, spraying the plants with water early in the day can control many pests, but be sure plants are dry when the sun goes down. Wet plants at night can create fungal and bacterial problems. Adding lots of organic matter prior to planting, planting green manure crops such as sunn hemp as a rotation, and practicing fallow can help to minimize nematodes. It’s also a good idea not to plant in the same area for a year or more to break the pest cycle and give the soil a rest.
You can tell the taro is mature by the size of the huli. After reaching a peak in their height, the plant will drop back and shrink down. The top of the taro corm will start to form a dome. If you have a lot of taro, it’s a good idea to start eating them before they’re fully mature, so when you get to the end of your field, the last taro is not over-mature. Some taro, like Moi or Piko types can be held in the field after maturity while Lehua and Mana need to be harvested when mature or it will start to rot quickly. Growing your own taro can be a very gratifying experience, and even more gratifying when you share it with others.