Mint rust Disease symptoms: Pale and distorted shoots in spring Dusty orange pustules on the stems and leaves. Pustule may change to dusty yellow or black in colour in later stage Large areas of leaf tissue die and plants may lose leaves Survival and spread: When the orange spore pustules mature and break open in June or July, the spores are spread to other plants by the wind. The fungus enters the plant through the leaves lNewly infected plants seldom show symptoms until the following spring. Favorable conditions: Dry weather with high relative humidity Pathogens overwinter on mint stubble & on wild mint. It spreads through propagation material and air Verticillium wilt Disease symptoms: Symptoms first appear in the foliage at the top of the plant. Symptomatic upper leaves are sickle-shaped and initially chlorotic or red, soon becoming necrotic. Premature defoliation and death of the plant can result. Vascular discoloration in stems and roots may be observed and diseased plants are often stunted. Survival and spread: The transport of infected planting materials can transmit the pathogen to long distances. Spread of the pathogen occurs primarily by soil and movement of soil and water. Favourable conditions: Verticillium wilt is favored by moist soils and a temperature range of 21-27° C. Micro-sclerotia are stimulated to germinate by root exudates of host plants Anthracnose Disease symptoms: Mint anthracnose, also known as "leopard spot". The fungus causes small, sunken brown spots to appear on the lower leaves and stems. These spots enlarge to form oval lesions with light gray centers and reddish-brown borders, and may unite. Mint anthracnose may cause defoliation and cankers, which may lead to splitting of the stem. Heavily-infected plants are weakened and oil yields are reduced. Anthracnose may become severe during wet seasons when the mint foliage is wet for long periods. Survival and spread: Conidia are rain-splashed from overwintering infected plant in the spring and throughout the summer to new growth. Favourable conditions: Infection requires three to twelve hours of wetness. Powdery mildew Disease symptoms: Powdery white patches are developed on the upper and lower surfaces of the leaves and stems. Under favourable conditions, the disease causes severe lossess. It also reduces the oil Survival and spread: Resting spores is responsible for primary spread and airborne spores for secondary spread. Favourable conditions: Disease becomes severe when weather is dry and air circulation is poor (warm and humid weather) Black Stem Rot Disease symptoms: Black stem rot is considered a moderate to serious problem in mint production. The fungus is most active during periods of cool and wet weather. Symptoms of infection include dark brown or black cankers on stems. Cankers may girdle the stem and cause plant parts above the infection to wilt and die. Survival and spread: Pathogen survive in soil and on plant tissue for many years by producing small (1 to 3- mm diameter), irregular-shaped, brown to black sclerotia. Favourable conditions: Disease become more severe in soils that are moderately wet and a temperature range of 15-25°C Stem and stolon canker Disease symptoms: Roots and stolon have brown or black progressively rotting areas. Plant stand may be greatly reduced. Survival and spread: Pathogen survive on crop debris and in soil as black to brownish resting structures (sclerotia) or as resting fungal mycelium. Favourable conditions: Warm soil with high humidity is favorable for disease development. Temperatures between 26-32°C, soil moisture between 30-60% and soil pH above 6.6 are conducive for disease development. Septoria leaf spot Disease symptom: Septoria leaf spots are dark brown/black, up to 3mm (⅛in) diameter and angular in shape (being constricted between leaf veins). Spores are sometimes visible within leaf spots on the underside of the leaf. Survival and spread: The fungus survive in plant debris and on weeds . Favourable conditions: Moist (more than 70% relative humidity) coupled with warm weather and intermittent rains favours disease development. Disease cycles: Mint rust Verticillium wilt Anthracnose Stem and stolon canker Powdery Mildew Black Stem Rot IPM for Mint To know the IPM practices for Mint, click here. Source: NIPHM; Directorate of Plant Protection, Quarantine & Storage