The IPM CRSP Funded by USAID
IPM CRSP Fourth Annual Report, 1996-97 Abstracts
Asia Region Annual Report: an Overview. George Norton, Ed Rajotte, Victor Gapud
IPM Activities in the Asia site are focused largely in the Philippines and, during the past year, were concentrated in four program areas:
- crop monitoring for arthropods and weeds in rice-vegetable production systems in San Jose, Nueva Ecija,
- multidisciplinary field experiments,
- multidisciplinary laboratory, greenhouse, and mircoplot experiments, and
- socioeconomic analysis and training.
The work was completed as a collaborative effort among scientists at the Philippine Rice Research Institute, the University of the Philippines-Los Banos, the International Rice Research Institute, the Asian Vegetable Research and Development Center, Penn State University, the Ohio State University, and Virginia Tech.
Research efforts are planned in the Philippines through a series of steps. The year four workplan was based on a prioritization of pests, crops, and constraints that was developed through a participatory appraisal process, a structured baseline survey, and crop monitoring in years two and three. Planning for collaborative research efforts for the year took place through discussions between U.S. and Philippines scientists at planning meetings in the Philippines, joint host-country/U.S. scientist two-page proposals, a workshop between U.S. and host-country scientists to integrate the two-page proposals into an overall plan and budget, and revisions to the plan following review by the scientists, the ME and USAID.
Field research is located in six villages in San Jose, Nueva Ecija, about a 15-20 minute drive from PhilRice. In year four, field research also expanded to the village of Bongabon, about an hour east of PhilRice. The host country site coordinator oversees the field research activities. U.S., UPLB, IRRI, and AVRDC scientists periodically visit the sites to work with PhilRice scientists on particular research topics. Laboratory and field research is also conducted at AVRDC in Taiwan, and student training takes place at Virginia Tech, Penn State, UPLB, and AVRDC. Short-term training also occurred at Ohio State in year four. Back to Contents
The arthropod community structure of rice-vegetable systems in San Jose, Nueva Ecija has been thoroughly studied. It has shown strong evidence of a rich diversity of natural enemies to insect pests of rice and vegetables during fallow and along the bunds, with flowering weeds serving as refuge and/or food for natural enemies in the absence of pests. The most common predators were spiders and crickets. Scavenger species, mainly Collembola and Diptera, equally abound and serve as food for arthropod predators. Back to Contents
Studies of the weed composition and the relative dominance of broadleaf, sedge, and grass species have been completed in three villages of San Jose with IPM CRSP farmer-cooperators. The differences in weed species and relative dominance among these villages were compared with available information of the weed situation in the same general area 20 years ago. In both rice and onion crops in Abar 1st, broadleaf species were dominant, followed by grasses and sedges. In Sto. Tomas, broadleaf weeds, sedges and grasses were almost equally dominant, but sedges were dominant in the onion crop. In Palestina, sedges were dominant over broadleaf weeds and grasses in rice. In the ranking of the twelve dominant weed species across sites, five are broadleaf weeds, three are grasses and four are sedges. A considerable carryover of dominant weed species across crops has also been observed.
An increasing shift of some dryland species into the irrigated lowland areas is apparent, owing to either scarce rainfall and inadequate irrigation waters during the wet season or to the alternate wet-dry crop rotation pattern that has been established in the area. This shift in weed composition has been accompanied by a change in species dominance. Back to Contents
Field Evaluation of Insecticide Treatments against Onion Thrips, Bean Podborer (Maruca testulalis), Eggplant Leafhopper (Amrasca biguttula), and Eggplant Shoot and Fruit Borer (Leucinodes orbonalis). V. Gapud, R. Suiza, E. Martin, E. Rajotte
Onion thrips densities in Tanduyong onion, which were very low throughout the growing season, did not differ significantly whether the insecticide (Brodan) was applied weekly, biweekly, triweekly, or not at all. Weekly spraying by farmers appears unnecessary and wasteful. The belief of farmers that sudden thrips population increases are induced by rain appears to have no factual basis as observed in farmers fields. Thrips pressure can be avoided if onions are planted at the proper time, i.e., December - January. Onions can be grown without insecticides for thrips control.
Population densities of nymphs and adults of the eggplant leafhopper, Amrasca biguttula, did not differ significantly whether the insecticide (Brodan) was sprayed twice a week, weekly, biweekly, or triweekly. The population trends in both nymphs and adults followed a similar pattern, starting with low-density levels, with peak densities at 10 and 14 weeks after transplanting. In PhilRice, both nymphs and adults started with high densities 6 weeks after transplanting and consistently declined thereafter, with no significant differences among treatments. The apparent differences in leafhopper population trends between farmers fields and the experimental field may be attributed to early planting in farmers fields and late planting in the experimental field, accompanied by weather factors. Varietal resistance may play an important role in leafhopper population changes.
A generally increasing trend in mite densities was observed in eggplant farmers' fields independent of insecticide treatments. This trend was more striking in the experimental field at PhilRice, indicating a preference of mites for older plants.
The total eggplant fruit production in farmers fields did not differ significantly whether plants were sprayed with Brodan or not. However, the mean weights of undamaged and damaged fruits, as well as the number of shoot and fruit borer larvae, differed significantly among treatments, among which T5 (damaged shoot and fruit removal) showed the highest mean weight of undamaged fruits, the lowest mean weight of damaged fruits, and the lowest density of fruit borer larvae. In the experimental field, eggplant fruit production and mean weight of undamaged fruits were slightly higher in T5, while mean weight of damaged fruits and density of fruitborer larvae did not differ between T4 (Brodan application of once every three weeks) and T5, although both differed slightly from other treatments.
Accumulated yields of eggplant over the season were higher in plots where young damaged fruits were removed every week (T5), suggesting a pruning effect. While the fruit damage levels among treatments reached 18.6% in farmers' fields, they were as high as 34.5% in the experimental field, except for plots where simple fruit removal was done, where they were 6.15% in farmers' fields and 7.1% in the experimental field. Simple regular damaged fruit removal by farmers appears to be more effective than insecticide application. Back to Contents
In mulched onion fields, the combination of one application of glyphosate followed by one hand weeding has been confirmed to be just as good as the farmer's practice of two herbicide applications (glyphosate and fluazifop) followed by two hand weedings, a cost-reducing and pesticide-reducing option for farmer adoption. However, onion yields did not differ significantly between treatments. Back to Contents
Field tests have shown that a combination of Bt and NPV is more effective against Spodoptera larvae than NPV alone, Bt alone, or Karate insecticide application. Larval counts were highest in Karate-treated plots and control plots, which did not differ significantly in these treatments. While yield differences were inconclusive, yields in Bt+NPV-treated plots and Karate-treated plots were comparable. The use of Bt+NPV and NPV alone is a promising option for Spodoptera management. Back to Contents
Impact of Rice Straw Mulch on Thrips Population, Seedling Damping-off Disease, and Germination and Growth of Weeds in Vegetables after Rice. V. Gapud, R. Suiza, E. Martin, L. Sanchez, M. Casimero, S.R. Obien, A. Baltazar, F. Bariuan, A. Watson, M. Mabayad, E. Rajotte, S. Miller, S.K. De Datta
Although onion fields mulched with rice straw did not show any apparent influence on thrips populations, thrips were slightly higher in mulched than in unmulched plots. A slightly higher percentage of stunted or less vigorous plants were observed in mulched than in unmulched seedbeds, but lower percentages of Fusarium infection was observed in seedbeds. In the field, however, transplanted seedlings had a higher percentage of stunting and Fusarium infection in farmers fields. In the case of weeds, mulching was observed to consistently suppress weed growth, particularly during the first few weeks after transplanting. Later in the season, mulching alone failed to suppress growth of broadleaf weeds. Overall, however, onion yields in mulched plots were three times higher than those in unmulched plots. Back to Contents
Effects of Rice Hull Burning on Soil-Borne Diseases, Weed Survival and Growth, and the Rice Root-knot Nematode, Meloidogyne graminicola in a Rice-Onion Cropping System. R.T. Alberto, L. Sanchez, E. Martin, M. V. Libunao, M.C. Casimero, S.R. Obien, A.M. Baltazar, F. Bariuan, A. Watson, M. Mabbayad, John Halbrendt, S.K. De Datta, S. Miller
Rice hull burning effectively killed nematodes up to a soil depth of 6 inches. Under field conditions, burning effectively reduced nematode root galls and densities in roots and soil. Likewise, weed emergence in unburned fields was greater by 74%, but extremely slow in burned fields, indicating that burning effectively destroyed weed seeds and propagules. Also, onion yields were almost 3 times higher in burned fields. Back to Contents
In crop rotation experiments, pink root infection in two farmers fields was 70% and 100%, respectively, with corresponding severity of 54.4% and 73.3%, while no infection was observed in mungbean and peanut 4 weeks after transplanting. Similarly, both mungbean and peanut were resistant to the nematodes. In the next crops of the treated sequences, M. graminicola densities in roots of cucumber and pepper were lower than those obtained from onion during the first cropping, indicating resistance of the two crops to nematodes. Nematodes remained in the soil from fallow plots, probably maintained by existing alternate weed hosts. Conclusions about the most effective rotation scheme cannot be made until all crop cycles are completed. Back to Contents
Nematode root galls and densities did not differ significantly among the biofertilizer treatments, although lower levels were observed in plots treated with VAM and Bio N. Although yields from biofertilizer-treated plots were slightly higher than plots with inorganic fertilizer, they did not differ significantly. Further tests will be completed.
Under greenhouse conditions, Tagetes and Crotalaria were effective in reducing nematode populations. Field tests were postponed for the next years onion season due to flooded field conditions. Back to Contents
Initial results of the use of castor as trap plants for Spodoptera litura larvae, showed that onion fields surrounded with castor plants had slightly lower cutworm larvae per plant than fields without castor, but the differences were not significant. Timing of larval sampling will be modified to acquire an accurate picture of larval density in onion fields. Castor plant catches, although erratic, went as high as 116 young cutworm larvae per leaf starting one month after transplanting, indicating a potential for castor as a trap plant for Spodoptera. Back to Contents
A field survey of parasitoids of Spodoptera litura, Maruca testulalis, and Leucinodes orbonalis in Luzon showed high egg parasitism of S. litura by Telenomus sp., very low parasitism of L. orbonalis by Trathala flavoorbitalis, and no parasitoids against M. testulalis, consistent with the heavily sprayed stringbean and eggplant fields of farmers.
Egg parasitism of S. litura by Telenomus sp. appears promising and will be explored when mass rearing of S. litura is underway. Back to Contents
Six isolates of Trichoderma sp. were obtained from farmers fields, two of which were found promising for disease control. Under laboratory conditions, T5 isolate was found effective in suppressing/parasitizing sclerotial bodies of Rhizoctonia solani, whether obtained from weeds or from rice. Greenhouse tests are being conducted to verify these results. Work at Ohio State University focused on isolation and identification of bacterial strains effective as biocontrol agents. Several strains were identified and characterized, as were the strains isolated by PhilRice scientists. We also isolated and characterized strains of the bacterial spot pathogen of pepper and tomato, Xanthomonas campestris pv. vesicatoria, which caused significant losses in field trials and also in commercial fields. This work provides a foundation for Year 5 field studies on onion disease management. Back to Contents
Further studies on the host range of Meloidogyne graminicola showed that out of 137 cultivars of 37 crops screened, 19 were resistant with a few susceptible cultivars in some crops, namely, bitter ground (except one cultivar), batao, bush sitao, carrot, corn (except one cultivar), cowpea (except one cultivar), cucumber, eggplant, hot pepper, sweet pepper (except one cultivar), kangkong, melon, peanut (except one cultivar), one cultivar of snap bean, squash (except one cultivar), and bottle gourd (except two cultivars) . Resistant crops are potentially useful for reducing nematode populations through crop rotation schemes. All of 30 onion cultivars studied were susceptible. Out of 40 weed species screened for resistance, only 12 were resistant, indicating that all major weeds of rice-onion system are alternate hosts of M. graminicola. Back to Contents
The increasing adaptation of the dryland weed, Cyperus rotundus, in irrigated lowland ricefields is evident in San Jose, Nueva Ecija. The growth of this weed under lowland condition is more robust, with more, longer, and larger leaves, more offshoots, larger culms, more flowers, larger tubers, and 50% more biomass under the lowland regime. When grown in pots under Laguna conditions, plants from Sto Tomas exhibited the same characteristics, but those from Abar 1st and Palestina did not exhibit any dramatic change in growth from upland to lowland conditions. However, plants collected from Laguna did not change in height but differed in having more leaves and offshoots, larger culms, more flowers, and more and larger tubers. Genetic analysis to establish whether two ecotypes or distinct genotypes are involved is currently being conducted at PhilRice. Herbicide tests to control C. rotundus plants and tubers are currently underway. Back to Contents
A preliminary survey was completed on intergenerational and gender differences and social networks that impact pesticide use and IPM adoption. The survey covered 31 farm households, including 45 male and 32 female members. A division of labor between male and female household members in on- and off-farm activities was evident. Power-intensive operations were handled by males and control-intensive ones by females. The generally chemical-based pest management practices were completed by males. Although the women did not physically participate in pest management operations, they took an active role in decision-making and control of household finances, which included the farm budget. Back to Contents
With departure of Prabhu Pingali
from IRRI, the data for the cost function analysis of
institutional changes affecting pesticide use were
transferred to PhilRice and cleaned up before analysis.
The model was developed, but the analysis still is not
complete. S. Francisco recently traveled for three weeks
to Virginia Tech for collaboration with G. Norton on the
modeling aspects. Back to
The economic profitability of the alternative management strategies to control pests (insect, weeds and pathogens) tested on the IPM CRSP in the Philippines were assessed using partial budgeting techniques. The results were that the majority of the proposed technologies have an economic advantage over the current farmers practices. Each of the experiments had at least one treatment with a higher yield, lower pesticide use, and higher net returns than the farmers practice. Back to Contents
A survey questionnaire to obtain information from Philippine households to estimate willingness to pay for pesticide reduction was completed and is now being administered in the Philippines. This survey is one part of the procedure to be used for estimating the economic value of health and environmental benefits of IPM practices developed on the CRSP. Back to Contents
A national vegetable IPM workshop
entitled: Symposium on IPM in Rice-Vegetable Systems:
Status, Constraints, and Prospects" was sponsored by
the IPM CRSP and held at the Philippines Council for
Agricultural Research and Development PCARRD, with 80
scientists and government agency officials in attendance. Back
The IPM CRSP Bibliographic Database and Search Service has continued to grow in use. A broad number of colleagues from CRSP and non-CRSP sites have discovered the service's availability, and several colleagues have become repeat users of the service. During Year four, we received 20 search requests requiring at least 90 database searches. This compares with the six requests that we received the previous year.
We have processed database searches for colleagues who are located at thirteen institutions in nine countries. These institutions do not include those of collaborators at the Philippines site. Three laboratories/colleagues have become repeat users of the service, and different individuals from the same institutions have submitted requests. Back to Contents
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