HomeInternational Rice Research Notesvol. 27 no. 1 (2002)

Efficiency and profitability of an IPM package against insects, blast, and nematodes in irrigated rice

K.b. Kaboré | D. Dakouo | B. Thio

Discipline: Agriculture



In Burkina Faso, major biotic constraints to rice production in irrigated conditions include insects, diseases, and nematodes. Lepidopterous stem borers (Chilo zacconius, C. diffusilineus, Maliarpha separatella, and Sesamia calamistis) can cause up to 33% yield losses (Dakouo et al 1991). A 1% increase in damage of the African rice gall midge is correlated with a 2% yield loss (Nacro et al 1996). Pot trials showed a yield loss of 30% caused by rice root nematode Hirschmaniella spinicaudata (Thio 1992). Rice blast (caused by Pyricularia oryzae) causes yield losses with an estimated value of more than US$10 million in West Africa (WARDA 1995). Pest control in irrigated rice still largely depends on the use of chemicals without meeting the necessary criteria of efficiency and profitability for small-scale farmers. Therefore, a cost-effective integrated pest management (IPM) package was developed by a multidisciplinary team to minimize reliance on toxic and expensive chemicals. This IPM package combines the use of local natural products made of organic manure (5 t ha-1) against nematodes, rice straw ash (2.5 t ha-1) against blast, dry neem (Azadirachta indica) leaf powder against nematodes, and alcoholic extracts of neem seed powder (200 g into 0.25 L of alcohol and 0.75 L of water) against insects. The efficiency and profitability of the package were evaluated during the 2000 wet season at two irrigated rice schemes, Banzon and Karfiguéla, near Bobo-Dioulasso, southwest Burkina. Its efficiency was optimized with the use of a rice gall midge-tolerant variety, BW 348-1. The IPM package (T3) was compared with two other treatments, T1 and T2. The first treatment (T1) was the control with no products against pests. T2 was a reference chemical treatment combining the insecticide Basudin (diazinon) at 1,000 g ai ha-1 in foliar sprays at 20, 40, and 60 d after transplanting (DAT), the nematicide Basamid (dazomet) at 100 kg ha-1 (incorporated into the soil 14 d before transplanting), and the fungicide Kitazin (di-isopropyl-sbenzil-thiophosphate) in a foliar spray at 720 g ai ha-1 at panicle emergence. The experimental design was a completely randomized block with three treatments and four replications, a plot size of 60 m2 (10 6 m), and plant density of 25 25 cm. Insect damage (deadhearts and onion shoots) was assessed at 40, 60, 80, and 100 DAT. Foliar blast was evaluated at 35, 49, and 63 DAT and neck blast incidence at 15 and 30 d after panicle emergence (DAPE). Nematode populations were estimated at the time of Basamid application—before transplanting and at 30, 60, 90, and 120 DAT.