What is Anthracnose?
It is a fungal pathogen that causes huge post-harvest losses in citrus and it is also known as Wither tip and die back.
Causal organism– Colletotrichum gloeosporioides
Susceptibility– All citrus species.
Symptoms-
- The disease attack leaves, young shoots and tender fruits.
- Affected leaves shows necrotic patches as circular, flat area, light tan in colour with a prominent purple margin.
- Dead part of twigs shows silvery grey appearance.
- Later defoliation and dieback of twigs occurs due to which it is also called wither tip
- At the advance stage branches show die back symptoms.
- The disease also affects fruit bearing stems and thereby, fruits too are affected.
- The fruit are characterized with black to brown spot with diameter of 1.5mm and greater.
Later the decay portion on fruit will lead soft rot.
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Fig- Symptoms of Anthracnose on leaves and fruits
Source- USDA (idtools.org)
Mode of spread-
- The wind helps in the translocation of spore.
- Close plantation and dense canopy help in the germination of the spores making it a congenial environment.
- The dried shoots and fallen leaves become media for transmission.
Reason of severity-
- Disease is mostly favoured by warm weather and cloudy weather at temperature of 300 -32 0 C, RH 80-85%.
- Rainfall also favours the spreading of disease
- Plants affected with gummosis are highly susceptible.
Management-
| Cultural Practices | Chemical Control |
| Remove and destroy all infected leaves, fruits and branches.Keeping the orchard clean and maintaining the vigour of the orchard.Adequate manuring & fertilizer application. | Spraying Bordeaux mixture (Copper Sulphate – 1 Kg + Slaked lime (Calcium hydroxide – 1 Kg + water – 100 liter) Spray (Azoxystrobin 11% + Tebuconazole 18.3% SC) @ 0.6ml per liter water. Mancozeb 75% WP @ 2g per liter of water is effective in controlling the disease.Spray Carbendazim 50% WP @-1.5gm per liter of water. |
Source –
Book – Handbook of Horticulture
