leaf spot

about the leafspots of hemp and olive spot

1. Leaf spot of Hemp

2. Botanical description of Hemp Cercospora cannabis Scientific classification Kingdom: Fungi Phylum: Ascomycota Class: Dothideomycetes Subclass: Dothideomycetidae Order: Capnodiales Family: Mycosphaerellaceae Genus: Cercospora Species: C. cannabis Binomial name Cercospora cannabis Hara & Fukui, (1927)

3. TYPES OF LEAF SPOT IN HEMP Olive leaf spot: Cercospora cannabis Pseudocercospora cannabina White leaf spot: Phomopsis ganjae Yellow leaf spot: Septoria cannabis Septoria cannabina

4. OLIVE LEAF SPOT Symptoms ; Cercospora cannabis  produces circular to elliptical spots, gray in the center with dark brown-black margins.  Conidia are produced in the gray centers.   Pseudocercospora cannabina  can cause complete defoliation.

5. Characteristic dark brown spots appear on the leaves. These spots are round to oval, irregular in shape and enlarge with concentric rings. The spots become necrotic leading to withering & drooping.

6. Etiology Mycelia septate, intercellular mycelia Asexual spores: whip like conidia Primary source of inoculum: Dormant mycelia. Secondary source of inoculum: Air born conidia.

7. Epidemiology The development of  leaf spot disease  is favoured by environment conditions like a temperature of 28-300 C, relative humidity 85-90%,cloudy weather and presence of susceptible host.

8. Management Cultural practices Cut the infected leaves. Mix recommended N:P:K doses in the cropping field. A total of 60–150 kg of nitrogen, 40–140 kg phosphorus (P 2 O 5 ) and 75–200 kg of potassium Drip irrigation system to be followed. Spray of Mancozeb (0.25%) or Carbendazim (0.1%). Mainly this disease is not severe but some FRANCE cultivars are resistant to this diseases