Wild Stevia is reasonably proof against predominant pest and illnesses, and steviol glycoside itself has sizeable pest repellant impact, modern high yielding breeds of Stevia desires crop safety to some extent. commonly, sub-most appropriate developing conditions, excessive moisture level in soil and air, weed infestation and unbalanced nutrients are triggers for pest and ailment assault. ideal vitamins and proper agronomic management often is the primary line of defence.
Stevia is reported to get infected by means of several fungal species, which may additionally result into full-size yield loss. some fungal pathogens for Stevia and their diagnostic capabilities are listed under.
- Alternaria alternata
- Light brown small circular spots that turn dark brown to grey and are circular to irregular in shape with concentric rings. Spots may coalesce forming large areas of necrosis.
- Sclerotinia sclerotiorum
- Wilting, chlorotic leaves, necrotic leaves at the base of the stem, and bleached stems. Symptomatic plants often have tufts of white hyphae present on stems and large, irregularly shaped 2 to 8mm black sclerotia on the base of the stem.
- Sclerotium rolfsii
- Yellowing and wilting of leaves, bleached stems, and eventual plant necrosis. White cord-like mycelia growth is visible at the base of stems, especially early in the morning. Mycelium is accompanied by the formation of brown sclerotia 0.5-2mm in diameter.
- Septoria steviae
- Shiny olive-gray foliar lesions, that are depressed and angular. Lesions often have a chlorotic halo and rapidly coalesce, turn necrotic, and leaves fall from the plant. Up to 50% of the foliage can become necrotic in severe cases.
- Rhizoctonia sp.
- Sunken reddish spots, gradually expand to kill the plants. Reddish-brown to brown collar rots and root rots are common in young plants. These rots inhibit normal growth and cause stunting or plants with poor vigor. Callus formation and thickening of the collar area also occurs.
- Fusarium oxysporum
- Wilting, chlorosis, necrosis, premature leaf drop, browning of the vascular system, stunting, and damping-off. Fusarium wilt starts out looking like vein clearing on the younger leaves and drooping of the older lower leaves, followed by stunting of the plant, yellowing of the lower leaves, defoliation, marginal necrosis and death of the plant.