Leaf (Ramularia) blight Disease symptoms: Symptoms first appear on the lower and older leaves in the month of January, as a minute, angular brown, necrotic spot. Later these spots become large and are covered with grayish white erumpent growth. At later stage, linear and rectangular spots cover the entire stem, peduncles and fruits. Severely affected leaves shrivel and dry up. In case of severe attack whole plant turns to brown colour, resulting in drying up of plant Survival and spread: Pathogen survives on infected plant debris in the soil Pathogen infects lower part first and then above plant parts It spreads through wind and rain splash. Favorable conditions: Disease favours high humidity >80%. Leaf spot Disease symptoms: The disease primarily affects older foliage. Affected leaf tips and stems turn brown to black in color and dry up. Examination of the stems and leaves show tiny, discrete, dark brown to black fungal patches. Early patches are less than one-sixteenth inch wide, and can be oval, circular or irregular in shape Survival and spread: Primary: Through dormant mycelium remains in the infected crop debris, seeds and volunteer plants Secondary: Through wind dispersed conidia Favorable conditions: Disease favours high humidity >80%. Damping off Disease symptoms: Damping off occurs in two stages, i.e. the pre-emergence and the post-emergence phase. In the pre-emergence phase the seedlings are killed just before they reach the soil surface. The young radical and the plumule are killed and there is complete rotting of the seedlings. The post-emergence phase is characterized by the infection of the young, juvenile tissues of the collar at the ground level. The infected tissues become soft and water soaked. Infected seedlings are toppled on the ground surface. Survival and spread: Primary: Through soil, seed, water Secondary: By conidia through rain splash or wind Favourable conditions: High humidity, high soil moisture, cloudiness and low temperatures below 24° C for few days. Crowded seedlings, dampness due to high rainfall, poor drainage and excess of soil solutes hamper plant growth and increase the pathogenic damping-off. Fusarium wilt Disease symptoms: Disease produces wilting symptoms at seedling and later stage of plant growth Infected plants turn yellow. Fungal growth may be seen in the infected plant stem if cut longitudinally Survival and dispersal: Pathogen is both soil and seed borne and survives as saprophyte in the soil debris as a mycelium and all spore types. It spreads short distances by water splash, planting equipment, and long distances by infected transplants and seeds. After the plant dies the fungus invades all tissues, sporulates, and continues to infect neighboring plants. Favourable condition: Soil temperature is between 12.5-14° C and high moisture Powdery mildew Disease symptoms: The disease symptoms appear at flowering stage in cloudy weather during February-March. The powdery fungal growth usually develops first on leaves which later can cover all succulent stems and branches including flowers. In severe case seed development may not take place. Survival and spread: Primary: Through soil and seed, Secondary: Dispersal of conidia through wind, rain splashes Favourable conditions: Cool high humid weather (20-25˚ C) or cloudy weather favours conidial germination and disease development High RH > 80% favours disease development. Collar rot Disease symptoms: Disease appears in plots where water stagnation near the plant stem is more. Collar portion of the affected plants start decaying and the plants turn to yellow colour & die later on. Later collar region of the plant/seedlings get rotted and plant topple down. Survival and spread: Primary: Dormant mycelium and fruiting bodies survive in the infected crop debris, seeds and volunteer Plants. Secondary: Irrigation disperses conidia to nearby plants. Favourable conditions: High humidity, high soil moisture and temperature Crowded seedlings Root rot Disease symptoms: Symptoms consist of seed decay and brown to reddish lesions on seedling stems and roots just below the soil line. These reddish brown lesions may become sunken and girdle the stems and kill the plant. Plants may often appear stunted and unthrifty and will die. Often the stand will appear uneven because of stunted plants. Disease is often found in patches in fields. On older plants, the pathogen causes a reddish brown dry cortical root rot that may extend into the base of the stem. Foliar symptoms may include yellowing or wilting of leaves. Survival and spread: The disease is mainly soil-borne and pathogen can survive in the soil as sclerotia for several years. Sclerotia disseminate by irrigation water, implements, and other cultural operations. Favourable conditions: Dry weather following heavy rains, High soil temperature (35-39˚ C) IPM for Fennel To know the IPM practices for Fennel, click here. Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage