— Written By Lindsey Thiessen

Root, Crown, and Stem Rot

Root, crown, and stem rots are being noticed in industrial hemp stands throughout North Carolina. Whereas a number of of those pathogens are opportunistic, many are extreme issues that may have impacts on future crops. At present, there are not any chemical administration instruments out there to producers that may economically scale back these pathogen pressures. Moreover, the usage of chemistries off label could lead to crop harm from potential phytotoxicity results or crop rejection from patrons. This data is to function a information to figuring out issues and supply some cultural practices which will scale back influence by these pathogens.

Fusarium wilt and crown rot (Fusarium spp.)

Fusarium wilt and crown rot are brought on by Fusarium spp. Damages related to Fusarium wilt and crown rot embody yellowing and wilting of leaves (Fig. 1) and vascular discoloration (Fig. 2). Root rots brought on by Fusarium spp. are most frequently related to different accidents to plant roots (i.e. environmental situations, nematode accidents, mechanical accidents from cultivation). Vegetation which can be over-irrigated or flooded from excessive climate situations could also be extra liable to damages. Equally, insect or nematode accidents could create wounds within the roots and crowns of vegetation that enable the fungus to colonize vegetation.

To scale back losses from Fusarium wilt or crown rot:

  • Restrict damages to roots by nematodes or root-feeding bugs
  • Keep away from bodily accidents to decrease stems or roots of vegetation with farming tools
  • Take away affected vegetation from fields and destroy crop particles shortly after harvest to restrict inoculum buildup

Determine 1. Wilting of hemp plant brought on by Fusarium spp.

Fusarium wilt vascular discoloration

Determine 2. Vascular discoloration of hemp crown brought on by Fusarium spp.

Southern Blight (Sclerotium rolfsii)

Southern blight/Southern Stem Rot is brought on by Sclerotium rolfsii, which has a large host vary together with vegetable, fruit, decorative, discipline crops, in addition to many weed species which will persist within the discipline. This illness causes the leaves to yellow and wilt, and the decrease stem exhibits indicators of necrosis (Fig. 3). In closely infested vegetation, small, brown BB-shaped sclerotia (overwintering buildings) might be discovered on white fungal mats on the base of stems (Fig. 3). This illness is favored by sizzling, humid situations, which have been persistent this rising season.

To scale back losses from Southern Blight:

  • Restrict damages to roots by nematodes or root-feeding bugs
  • Keep away from bodily accidents to decrease stems or roots of vegetation with farming tools
  • Take away affected vegetation and any fungal buildings which can be surrounding the vegetation from fields and destroy crop particles shortly after harvest to restrict inoculum buildup
Southern Blight of Hemp

Determine 3. Industrial hemp crown affected by Sclerotium rolfsii. Picture courtesy of Eli Snyder, Caldwell County Extension Agent

Pythium Root Rot (Pythium spp.)

Root rots brought on by Pythium spp. are frequent in situations with extra moisture or with a historical past of Pythium root rot. This fungal-like organism has spores that may transfer in water. Extra water surrounding hemp root techniques make them extra inclined to illness, and the water permits pathogens like Pythium spp. to entry the roots extra simply. This may be present in greenhouse and discipline manufacturing techniques, and might trigger important harm to vegetation. Vegetation yellow and wilt, and the roots grow to be brown and necrotic. For extra data on Pythium root rot, see the Pythium Root and Crown Rot of Industrial Hemp Reality Sheet.

To scale back losses from Pythium Root Rot:

  • Restrict damages to roots by nematodes or root-feeding bugs
  • Keep away from extra water round roots and keep away from watering from ponds, lakes, or streams as they could be a supply for this pathogen
  • Take away affected vegetation from fields and destroy crop particles shortly after harvest to restrict inoculum buildup

For particular questions relating to industrial hemp illness administration, contact your native cooperative extension agent.