Evaluation of maize cultivars and rotation crops for resistance to damage by fungus-growing termites

Abstract

The fungus-growing termites, Microtermes spp. and Allodontermes spp. are important maize pests in sub-Saha- ran Africa. The use of sunflower and sorghum as alternate or rotation crops with maize to reduce termite infestations was evaluated in field trials in South Africa during 1995/96 to 1999/2000 seasons. Termite damage patterns on these crops were determined throughout the season by uprooting and inspecting root systems for termite damage at regular intervals. The incidence of lodging was determined at harvest. Damage to sorghum and sunflower plants commenced at a later stage than maize and the rate of increase in incidence of damage was slower in these two crops. Incidence of lodged plants at harvest was 100% for maize, 1 % for sorghum and 0.7% for sunflower in the 1998/99 season. Significant differences in the incidence of lodging were observed between different maize cultivars under low termite infestations. At high infestation pressure, the incidence of lodging was higher than 85% for all maize cultivars. No lodging was observed for sorghum or sunflower cultivars during the 1999/2000 growing season. Incidence of damage to root systems and subsequent lodging of maize plants planted on fields previously planted to sunflower and sorghum was similar to that of maize planted on a field previously planted to maize, indicating that the former two crops do not suppress termite activity in subsequent seasons. Economic analyses indicated sunflower to be the most profitable crop to cultivate in fungus- growing termite infested fields.

Key words:

• Maize
• sorghum
• sunflower
• termites
• Microtermes sp