Fungal Leaf Spot in pants: Top Cause and Best Treatment
Image Source: David B. Langston, University of Georgia, Bugwood.org, CC BY 3.0 US, via Wikimedia Commons (Image Cropped)
Fungal Leaf Spot in plants is caused due to fungal pathogens. The leaves develop small brown spots with yellow margins. The spots can have concentric circles. The symptoms may vary as per the species that infect your plant. In dead tissue, tiny black dots (the fruiting bodies of fungi) may be visible. The lesions run together often and the whole leaf dies. The fungi live in the field on dead and rotting plant matter.
Causes of Fungal Leaf Spot in plants:
The fungal leaf spot is caused by fungal pathogens belonging mostly to the fungal genera Cercospora Alternaria, Colletotrichum (anthracnose), and Myrothecium. As fungal spores in the air find a warm, wet, plant surface to adhere to, spotted leaves occur. Sporulation (the fungal form of reproduction) happens as soon as the microscopic spore gets relaxed in its new home and the tiny brown fungal leaf spot starts to develop.
The spores are attracted to the surface of plants that are rich in moisture or have moisture content. Excess watering, moisture and lack of proper air circulation can be the causes for the fungal spores to develop and grow in the leaves. Thick bushy plants which lack proper air circulation and light can also be home to these pathogens.
Signs and symptoms of Fungal Leaf Spot in pants
The symptoms include development of brown or black spots which are formed as concentric circles on the infected area. The spots develop yellowish margins around. As the infection spreads, under wet conditions the spots spread and covers the whole leaf, under dry conditions the spots have a speckled appearance. As spots become more numerous, entire leaves can yellow, wither and drop. The symptoms may vary according to the species that infect the plant.
In Cercospora lesions first appear as light green sunken spots which, with the development of spores, turn grey and darken. They may also have a purple rim, and tend to be raised in the middle. Lesions can coalesce into necrotic V-shaped regions that can be confused with bacterial blight. Leaves which are heavily infected can drop.
In Alternaria, the leaf spots are seen in conditions that stress host plants such as high or low temperatures or closed boxes during shipment. On the lower, older leaves, tiny water-soaked spots first appear. They become sunken and turn brown as the spots develop, often with a yellow halo. It may or may not appear that the spots appear in concentric circles. Spots can coalesce in extreme cases, causing the leaf losing color and eventually.
Anthracnose diseases are the product of Colletotrichum and Gloeosporium fungi. Shoot dieback, stem splitting, and the inability of young leaves to extend are the symptoms that follow growth distortions. On petioles and pedicels, thin, brown lesions can be seen. In infected petioles and corm, vascular discoloration is obvious. On leaves and petals, small, circular lesions spread to form large areas of necrotic tissue. Leaves and petals can become totally blighted. The existence of pink to orange sporulation oozing from lesions under close examination is a diagnostic indicator for anthracnose. It can be transmitted as a saprophyte in injured tissue on infected seeds or rhizomes, or derive from infected plants.
Myrothecium are soil-borne saprophyte and are considered a vulnerable pathogen that in optimal environmental circumstances invades wounded or stressed plant tissue. Chlorosis, stunting, low plant vigour, wilting, and breakdown of plants are common symptoms in plants infected with Myrothecium. In certain plant species, it may also cause root and crown rot and can cause cuttings to be lost during propagation. Lesions, with light brown centres and dark edges, are also target-like. In the lesions, distinctive dark green to black sporodochia (spore-producing structures) edged by white hyphae form.
Treatment and Management of Fungal Leaf Spot in pants:
- For the control of leaf spot disease, good hygiene practices and humidity reduction in and around the plants are important.
- Reduce the relative humidity in the greenhouse and within the canopy of the plant.
- Reduce leaf wetness by watering or sub-irrigating early in the day. Avoid overhead spraying.
- Providing good air ventilation by adequate plant spacing inside the plant canopy and the use of fans to provide horizontal air flow also helps.
- Remove and kill all highly infested plants.
- Diseased plant residue should be collected from the growing area quickly. Stop touching plants while they are damp. When they are available, grow resistant cultivars.
- Do not re-use media or pots that are rising.
- Use a mild fungicide to reduce the spread of the disease.
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