IPM is Easier and Cheaper Than You Think
Farmers who are not yet practicing integrated pest management or IPM may as well follow the innovators to enjoy the numerous benefits from it. It is a lot easier and cheaper than you think.
IPM may be defined as an agro-ecological method of sustaining the long-term benefits of rice production through the use of different techniques on managing of rice insect pests and diseases without causing any damage to the environment.
For a start, learn the interactions of the rice crop with biotic factors, the agroecosystem, and the crop management system to understand the destructive potential of pests, according to PhilRice experts. Remember that pest management is an integral component of rice production.
Identify pests correctly and apply integrated crop management technologies like use of resistant varieties, land preparation, date and method of crop establishment, biological control, varietal rotation, fertilizer and water management, and pesticides-to successfully follow IPM.
The common insect pests in ricefields are white stemborer, yellow stemborer, rice black bug, green plant hopper, brown plant hopper, whitebacked plant hopper, and rice bug. Likewise, the common diseases are brown spot, blast, sheath blight, bacterial leaf blight, neck rot, and tungro. After feeding on infected plants, green plant hopper spreads the tungro virus disease.
PhilRice’s handbook “PalayCheck System for Irrigated Lowland Rice” states that the use of resistant varieties is the first line of defense in pest management and is compatible with biological control. Change or rotate varieties every 2-4 croppings to delay insect pest and disease adaptation and, hence, prevent build up of virulent disease organisms and insect pests.
Likewise, adopt synchronous planting scheme after a fallow period in the locality. Allow a fallow period of at least a month from harvest to the establishment of the next crop. This can break the pest cycle and facilitate the success of crop management practices. Synchronous planting requires farmers in a locality to plant within one month after the fallow period.
Also needed is the conservation of beneficial organisms as there are rich communities of these organisms in the rice ecosystem in the absence.of insecticides that kill natural enemy of insect pests. “The indiscriminate use of pesticides reduces biodiversity and disrupts the natural balance of insect pests and beneficial organisms,” the handbook states.
It adds that conservation of beneficial organisms is safe, economical, and permanent. For example, the long-horned grasshopper feeds on the egg mass of stemborers, while spiders feed on the nymphs and adults of leafhoppers and planthoppers. Other beneficial organisms include the damselfly and wasps.
Moreover, conduct regular field monitoring, especially at the early stage of crop growth to identify the potential pests at its initial stage of development. Apply preventive management options before diseases spread and reach intolerable levels. Correct management options are recommended for insect pests.
Do not spray against defoliators (insects that feed on the leaves) during the first 30-40 days after transplanting. Plants compensate early season damage by producing new leaves and tillers. Spraying prevents the movement and colonization of beneficial organisms in the field during the early season.
To manage diseases, farmers must diagnose diseases correctly and practice field sanitation to help prevent the spread of diseases. To diagnose diseases, compare the appearance of an infected plant with other plants of the same variety and age. Consider disease distribution, spread, and condition of the field. It also helps to examine the infected plant closely and see if there are other organisms on it.
To minimize disease severity, avoid too much application of nitrogen fertilizer. The diseases bacterial blight, sheath blight, and blast can be reduced indirectly by basing nitrogen application on LCC (leaf color chart) readings.
To minimize insect pest and disease occurrence, avoid the following: too much nitrogen application, three croppings a year or short turnaround period, and unnecessary use of pesticides.
The presence of rats can be indicated by active rat burrows, footprints, cut tillers, and runways. Use the trap barrier system (TBS) to monitor rat population. A TBS can be a guide to start rat control operations if it is established one month before the regular cropping season.
Practice the following to effectively manage field rats: proper timing, active and sustained community-wide control, use of flame thrower, hunting, baiting, trapping, and cleaning.
To effectively manage the golden apple snails, take note that the snails feed only on young rice seedlings. Thus, keep the field saturated within two weeks after transplanting or three after direct wet-seeding so that the snails would not move around and feed on the seedlings.
Construct small canals and place newsprint as well as banana and gabi leaves that would attract the snails; it would be a lot easier to collect the snails this way. To prevent the entry of snails into the field, place wire or woven bamboo screen at the water inlets and outlets.
To reduce the weed population, practice the following: proper land preparation, land leveling, water management, use of healthy and clean seeds, varieties with good early vigor, and sound and appropriate use of agrochemicals.
PhilRice experts say weed control is critical during the first 40 days after transplanting or first 30 days after direct wet-seeding.
The most common weeds in irrigated farms are Monochoria vaginalis (known as gabi-gabi, bilugut, or lapalapa), Sphenocloa zeylanica (known as mais-maisan or sili-silihan), Cyperus rotundus (known as sudsud or gumi), and Echinocloa crusgalli (bayakihok).
According to PhilRice experts, significant yield losses would occur if
1. rats have damaged 5 percent or more of the tillers in an area from maximum tillering to maturity;
2. snails have eaten or damaged 10 percent or more of the newly transplanted or newly wet-seeded seedlings at 14 days after transplanting (DAT) or after seeding;
3. about 10 percent or more of an area has weeds at 15 DAT or 30 days after seeding;
4. about 5 percent or more of an area has damaged panicles.
When monitoring the occurrence of key rice pests from planting to harvest, watch out for these damages.
Stemborer (14-28 DAT). Infected plants have deadhearts or yellow young leaves at the center of the tillers. If the yellow young leaves have rusted or have black dots on the lower surface, it is caused by zinc deficiency.
Rice tungro disease (21-45 DAT). It results in stunted plant with greenish to yellow top leaves. All the leaves of plants affected by nitrogen deficiency, on the other hand, are yellowish green but have brownish leaf tips.
Rice leaf blast (21-45 DAT). It causes greenish diamond lesions with yellow margin on the leaf surface. Later, the lesions fuse together and turn dark brown.
Brown spot ((21-45 DAT). Lesions of brown spot appear; these are solid dark brown from the very start.
Rice black bug (35-70 DAT). It results in dead tillers. Lower leaves or entire plant have burnt-like appearance, and surviving plants produce panicles with empty spikelets.
Bacterial leaf blight (45-90 DAT). Yellow spots along the leaf margins appear. They enlarge later, fuse and turn brown, and run lengthwise towards the base of the leaf.
Collar or neck rot (70-90 DAT). This is the occurrence of brown to dark brown lesions at the base of the flag leaf and panicle with unfilled or half-filled straw-colored spikelets. Empty spikelets caused by stemborers are white.
Rice bug (75-100 DAT). It causes unfilled or half-filled spikelets; filled seeds might be damaged with chalky grains as a result of rice bug feeding during the milking stage.
You can learn more about insect pest and disease levels associated with significant yield loss from the PalayCheck handbook for irrigated lowland rice.
To be able to correctly identify insect pests, get hold of a copy of PhilRice’s Insect Pest Diagnostic Kit by Dr. Truong Hoai Xuan, Herminia R. Rapusas, Dr. Rolando T. Cruz, and Dr. Lina B. Flor-Weisler. The kit is available in Filipino, Iluko, Cebuano, and English. Likewise, get a copy of the handbooks on PalayCheck System and Palaytandnan from the nearest PhilRice branch station. Photos of the common insect pests are also included in the PalayCheck handbook for irrigated lowland rice.