Reflecting generally good rainfall since late July, crops are developing satisfactorily in most producing areas of Mauritania, Mali, Burkina Faso, Niger and Chad. Crop prospects improved in Senegal and The Gambia but rains need to last until October to cover the crop growing cycle, following the late start of the rainy season and subsequent reduced rains.
Grasshoppers are reported in almost all countries. Treatments have been undertaken in some areas. Grain-eating birds are also present in Mali and Senegal. The Desert Locust situation remains calm. Only small numbers of locusts were reported during August in southern Mauritania and in northern Mali. Good rains received in August throughout the summer breeding areas of Mauritania, Mali, Niger and Chad will improve breeding conditions. Consequently, locust numbers will increase but remain at a low and non-threatening level.
Following successive localized poor harvests in several countries of the Sahel and in view of weather anomalies in other regions due to El Niņo and La Niņa phenomena, the 1998 crop season in the Sahel appears particularly sensitive this year. Therefore, in collaboration with Club du Sahel and FAO, the CILSS secretariat launched during a regional meeting on food strategies in the Sahel in June, a special initiative to monitor the 1998 crop season. In each country, a team has collected during August data on the evolution of the season in order to prepare a report which will be presented at a regional meeting from 21 to 25 September in Niamey, at the Agrhymet Centre. This meeting will provide an opportunity to get a first assessment of harvest prospects and discuss the preparation of the usual FAO-GIEWS/CILSS-DIAPER crop assessment missions scheduled in each country from mid-October. The final results of these missions will be presented during a regional meeting organised by DIAPER in the Sahel in mid-November and will then be discussed with representatives from the international community during the annual meeting of the network for Prevention of Food Crises in the Sahel in early December in Dakar.
Sahelian zone: Where average annual precipitation ranges between 250 and 500 mm. This zone is at the limit of perennial vegetation. In parts where precipitation is less than 350 mm, only pastures and occasional short-cycle drought-resistant cereal crops are grown; all cropping in this zone is subject to high risk.
Sudano-Sahelian zone: Where average annual precipitation ranges from 500 to 900 mm. In those parts of this zone where precipitation is less than 700 mm, mostly crops with a short growing cycle of 90 days are generally cultivated predominantly sorghum and millet.
Sudanian zone: Where average annual precipitation ranges from 900 to 1 100 mm. In this zone, most cereal crops have a growing cycle of 120 days or more. Most cereals, notably maize, root and cash crops are grown in this zone.
Guinean zone: Where average annual precipitation exceeds 1 100 mm. Guinea-Bissau and a small area of southern Burkina Faso belong to this zone, more suited to root crop cultivation.
Reference will also be made to the Intertropical Convergence Zone (ITCZ), also known by its trace on the earth's surface, called the Intertropical Front. The ITCZ is a quasi-permanent zone between two air masses separating the northern and southern hemisphere trade winds. The ITCZ moves north and south of the equator and usually reaches its most northerly position in July. Its position defines the northern limits of possible precipitation in the Sahel; rain-bearing clouds are generally situated 150-200 km south of the Intertropical Front.