The disease is caused fungus disease causing organisms by Sephora cannabis and S. Neocannabina, they are pathogens that attack marijuana only. It attacks plants that are growing in the open, in areas where it is warm and it rains. It also attacks plants which lack enough supply of nitrogen. The disease initially appears on the lower side of the leaves. The spots appear white others gray and others are yellow in color. As the spot gets older it appears as a pimple which is larger than the initial spot.
The disease attacks the leaves and destroys them then moves on to the stem of the plant; however it does not destroy the plant to death. It makes the plant to reduce in productivity, the leaves dry on the place where the spot was and a hole appears on the spot. Leaves which have been heavily affected dry up then fall off. The spores that cause the disease are spread by wind which blows them away to infect other leaves; they are also spread by water and passersby.
Prevention of yellow leaf can be achieved by practicing crop rotation. This means that after every harvest the plant should be planted in a different area. If the space available may not allow this crop rotation then, after harvesting the crop clear all traces of cannabis from the environment until the soil regains its nutrients. Now you can prepare the land to ensure that the plant has enough nitrogen for the germination of the new crop. Nitrogen for the soil can be provided by spreading fish meal, and blood meal or soybeans on to the ground. Always ensure that you clean your farming kit with rubbing alcohol or try peroxide.
Also you may try to spray fungicide before planting a new plant. The fungicide will kill all pathogens as you prepare the land for planting. There are many mixtures that you can use as fungicide or purchase already mixed solutions. Mixtures that you can uses include oil with other bases like, cinnamon, neem, sesame or cloves and coriander. To prevent spores of yellow leaf spot from growing in the area you can spray baking soda mixture or compost tea.
When watering the plants ensure that you water the soil and not the leaves of the plant, also ensure that watering is done either in the early morning or in the early evening. This will ensure that the leaves are not burnt by sunrays. This should be done even when farming other crops, watering should be on the soil and not the leaves.
If the yellow spots attack the plant during the harvest period, then remove all the affected leaves in the plant and destroy them fully. Also spray the infected areas with the fungicide of your choice for those discussed above in the article.
This will help cannabis farmers to cultivate their crop well and maximize their yield in cultivation of marijuana.