*5.4.1.1 Management of Fusarium wilt*

Treatment of seed with chemical fungicides and planting resistant varieties are measures that can be used to manage the disease. Hot water treatment of seed at 52 °C for 30 minutes and crop rotation with distantly related crop is also helpful.

#### **5.5 Genus:** *Pythium*

Members of the genus *Pythium* are common worldwide [92]. Many species in the genus *Pythium* are important soil-borne pathogens which affect economically important crops such as cereals and vegetables [93]. Several other *P*ythium spp. are saprophytic, with some enhancing plant growth and displaying potential as a biocontrol agent [94]. About 8 *Pythium* species have been identified in Africa, *P. aphanidematum* being the commonest. Pythium-induced damping-off and root disease of cucurbits cause huge losses, sometimes as much as 100% [95].

#### *5.5.1 Damping-off in cucumber*

Damping-off caused by *Pythium* spp. constitute major constraint to cucumber production worldwide [96]. *Pythium* spp. were associated with wilt and root rot

of hydroponically grown crops, including cucumber in South Africa [97]. The infection can occur before or after seeds germination. At pre-emergence, rotting of seed inside seed coat occurs. At post-emergence, damping-off appears as yellow to dark brown and water-soaked lesions are noticed on the root and hypocotyl tissue. With time, further root decay occurs, the hypocotyl shrivels and the seedling wilt. Inoculum of *Pythium* spp. can be transmitted from one place to another through airborne dust, soil, water, farm tools and equipment.
