STEM or fusarium wilt of sweet potato (Ipomoea batatas (L.) Lam. is an important disease caused by the fungus Fusarium oxysporum f. sp. batatas. This fungus is soil-borne and can survive in the soil for several years.
Fusarium wilt is the number one cause of vascular wilt characterized by the interveinal yellowing of the leaves followed by complete yellowing of the lower, older leaves. Infected vine stem ruptures with brown to purple discoloration. This disease was first reported in Kayapa, Nueva Vizcaya in 2011 with 30 to 85 percent disease incidence in affected villages (Backian et al. 2014). This disease fairly spread through the movement of infected planting materials.
Sweet potato farmers in Kayapa, Nueva Vizcaya describe this disease as nappit that slowly spreads until the whole plant dies. According to them, sweet potato roots harvested from infected plants taste bitter with foul odor and colored black.
Clean planting materials of three sweet potato varieties namely; Gislayan, Atok and Pakak were used in a demonstration farm in Besong, Kayapa, Nueva Vizcaya which was done January, 2016 to counteract the infection of fusarium wilt.
Variety Gislayan gave an 88.41 percent increase in storage root yield. Likewise, the use of clean planting materials also gave a minimal percentage in disease incidence. The varieties mentioned are continuously produced at the Northern Philippines Root Crops Research and Training Center at Benguet State University, La Trinidad, Benguet.
Clean planting materials of sweet potato are produced from in-vitro plants. One-month-old in-vitro plants are transplanted in greenhouses as mother plants and rapidly multiplied through single node cutting technology. Single node cuttings (SNC) are rooted or pricked in trays or beds with sterilized soil mixed with carbonized rice hull or organic matter. The SNC are transplanted in the field after 10 to 15 days.
Degenerated varieties can be submitted to the Northern Philippines Root Crops Research and Training Center for clean-up and regeneration especially the elite varieties. To date, there are 179 identified indigenous varieties of sweet potato in Northern Luzon.
By Northern Philippine Root Crops Research & Training Center, BSU