Alternative IPM methods for rice-onion crops developed

Alternative integrated pest management [IPM] practices developed by PhilRice [Philippine Rice Research Institute] researchers can very well fit into the current farming practices of onion farmers and reduce pesticide application.

The researchers have successfully integrated the alternative IPM practices in rice-onion cropping systems at the farm level for eight years.

The IPM strategies that can reduce pesticide inputs in onion farms are:

1. Alternative weed management strategies that can reduce herbicide application and lessen handweeding cost by as much as 50 to 60 percent. These include the stale seedbed technique, rice hull burning, and rice straw mulching combined with one herbicide application and one handweeding.

2. Insect pest management strategies to manage the common cutworm have been shown to be beneficial as well. These include the use of sex pheromone traps to monitor insect pest populations, the use of nuclear polyhedrosis virus [NPV] spray based on damage level, and non-application of insecticide in the first 20 days after transplanting [DAT] onion.

The PhilRice researchers involved in this project are Dr. Madonna C. Casimero, Rizal G. Corales, A.O. Capistrano, Leilani M. Juliano, Dong Arida, and Herminia Rapusas.

Efforts are now exerted to introduce these technologies to more onion farmers, especially in Ilocos Norte, Ilocos Sur and Nueva Ecija where onion is an important crop after the wet season rice.

The project involves the active participation of farmers so that they can readily evaluate the alternative IPM strategies and select those that would fit well into their practices.

Also included in the project are preventive measures against disease.

It is hoped that direct involvement of farmers in the project would make them easily understand the scientific basis of these technologies and how these would increase their yields and profits as well as promote the sustainability of their farming system.

The stale seedbed technique is done by plowing the field after the rice harvest followed by harrowing. The field is left undisturbed for two to three weeks to allow the weeds to grow. When the mutha plants have six to eight leaves already, the farmer harrows the field again, followed by another harrowing at one week before transplanting. The herbicide oxyfluorfen is applied at seven to 14 DAT. The spaces between rows are cultivated at 53 DAT.

Experimental results of the researchers have also shown that for the control of the common cutworm and bean pod borer, farmers need not spray at low damage level. The yield of unsprayed onion was not significantly different from that of onion sprayed twice with insecticide. 

Results also showed that NPV [30 ml/liter of water] is as effective as insecticide in controlling common cutworm. Moreover, NPV does not pose any danger to human health.

The researchers also reported that net income derived from the IPM plots was higher by 14 to 23 percent than that from fields sprayed with insecticide. 

They stressed that although the cost of the alternative technology is higher in some cases, the economic benefits are also higher than in the farmers practice. Moreover, the alternative technology offers added benefits like safety to the farmers, consumers and the environment because of reduction of chemical sprays, as well as proper timing and rate of application.

While the alternative technology reduces the cost of production by a very modest seven percent, increased yields and income are substantial. —– Sosimo Ma. Pablico