Fungi is everywhere. Some types are beneficial to our precious grows, and some can be very destructive. Fungi grows quite fast, and if left untreated, it can cause a big headache and cut your yeilds down by alot. Some pathogens can spread so fast they can take over your entire crop in a week. Cannabis is affected by many, many different types of fungus. At least 88 different types of fungi are known to attack the cannabis plant. Some areas of the United States are effected more by powdery mildew, while others have more of a Botrytis problem. Fungi can infect through many different ways; unpasturized soil, very high humidity, insects, and airborne spores. Some prefer cool, humid tempratures while some prefer hot and humid tempratures. It can be a very tricky thing to cure. Fungi is most prevailent during the spring and fall seasons. Keeping your humidity in your grow rooms (60% in veg, 40-50% in flowering) is one way to help keep airborne fungi minimal. Using pasturized soil can help, but you never can know how clean the soil really is. I personally have seen fungus gnats flying around bags of soil (in the store) from companies who claim they have "pasturized" their soil. In humans, the second biggest cause of death is by infectious and parasitic disease (like malaria). This is only surpassed by cardiovascular diseases. Bugs will probablly be the root of all evil in your grow room, spreading spores everywhere. Crawling bugs (like spider mites) can spread fungi all over your plant by crawling to leaf to leaf. Winged bugs (like whiteflies) can spread it from plant to plant. Some denser types of cannabis are more prone to rot, because denser buds hold more moisture. Grey mold, Budrot, gray blight, or scientifically Botrytis cinerea is usually the infectious pathogen. There are many types of Botrytis, but B. cinerea is the most common. Botrytis types of fungi spread by spores becoming dislodged from the main infection point and spread to neighboring plants. There is no way to cure a part of bud that has been infected with the Fungus. It is also very hard to clean. The only thing to do is to remove the area infected with the fungus. After you remove the infected area, you should treat the sorrounding plants in the area for the Botrytis fungi. High humidity can cause the spores to become more active, so lowering the humidity may prevent it from spreading. The fungi spores can stay dormant for some time after the fungi is removed. Even if there is no host for the fungi it can still live; the spores don't need living matter to survive. Just like how spider mites and other insects can be anywhere after treatment, botrytis is the same. One natural (but pricey) way to combat botrytis is a product called Employ. Over time, plants accumulate Pathogenesis-Related (PR) protiens. One PR, called harpin, is enhanced and is the active ingredient in Employ. Other than just Botrytis it can help control powdery mildews, leaf spot, ect. Spores fall downward onto the lower leaves and onto the floor, or soil. Taking off a layer of your topsoil and throwing it away can help. Good ventilation can also help prevent this bold from happening. Also, a thorough cleaning of your room with bleach will kill any spores on contact. Root rot is a waterborne disease that can cause a crop to fail very quickly. Fusarium Solani Rhizoctonia solani Sclerotium rolfsii Root rot chokes out the roots by attaching itself to the root, making water and nutrients hard to get absorbed by the plant (if it could get abosorbed at all). Root rot also causes the pH to fluctuate. In late stages of root rot the base of the plant will start to rot, which will make the plant unsturdy and it will fall over. Roots can never come back alive, but the plant will grow new ones. Tips of the plant will appear burnt if your plants are succumbing to root rot. Aeration of your medium can help prevent root rot. Enzymes like Hygrozyme or Sensizyme will help prevent root rot. H202 (hydrogen peroxide) can also be used as a good way to control Root Rot, but if you have any beneficial bacteria in your soil the H202 will kill it off. Poor drainage can also be a cause of root rot, so make sure your pots are kept well drained. One product, called RootSheild by BioWorks, Inc. contains a fungus fungicide (its a fungi eat fungi world), called Trichoderma harzianum. This fungi can be used in the manufacture of enzymes. Leaf Spot Leaf spots shouldnt kill your crop, but it will harshly diminish your yield. There are many different kinds that can effect cannabis, but they are mostly from the Septoria family. Avoiding overhead water will help reduce your chances of getting Leaf Spot. Leaf spot is quite uncommon indoors. Applying a small ammount of baking soda as a foliar spray will also help with leaf spot. Bacillus subtilis can also be applied to help combat leaf spots. Powdery Mildew Low humidity levels and ventilation can help prevent powdery mildew. Powdery mildew is easier to clean off than Bud Rot is, but it spreads faster and is just as harmful. It is a white color that starts to show up in spots on your leaves. It usually starts in the summer and continues on through the fall. It is worse in shaded areas and areas recieving no air movement. It doesnt need humidity to live, so it can thrive while it is hot and dry. It blocks photosynthesis and causes stunted growth + stretching. PM can also get on buds, causing them to become infected. Using baking soda as a foliar spray can help prevent powdery mildew from sticking to your leaves, because of the raised alkalinity. Potassium bicarbonate will also do the same. I have a friend who says he uses alot of a product called Serenade, which contains the QST 713 strain of Bacillus subtilis. Neem Oil can also be used to help control powdery mildew. Hemp canker Sclerotinia sclerotiorum -big thanks to Atomic Bong !!!!!!!! Hemp canker can litlerally eat your plant in half. It is mostly associated with European and growers in India. It first shows up in late summer as a large, canker sore looking thing on your stalk. White mold will start growing on it and the stem will appear black all around the mold. The stem will become very weak and wont be able to hold up its own weight anymore, and it will fall. Removing all fallen and dead leaves from your soil will help reduce the risk of getting hemp canker. Also, adding more soil to your plant throughout your grow can help reduce the risk of canker. S. Sclerotiorum cannot grow 6cm beneath the soil. Composting must be done correctly, or using pasturized soil is your best bet not to catch this problem. A product called ContansWG contains a bacteria called Coniothyrium minitans, which is a parasite to S. sclerotiorum. If infection is too bad, it is reccomended to completley cut off the infected area from the plant (unfortunatley, yes that means cut your plant in half) Damping Off Damping off has to stages: Pre-emergent and Post-emergent. One starts in the soil when the seedling is planted. The other emerges when the seedling has grown a bit more. The primary fungi involved in Damping off are Rhizoctonia solani, Botrytis cinerea, Macrophomina phaseolina, Pythium aphanidermatum, and Pythium ultimum. Fusiarium fungi can also cause dampening off, including Fusarium avenaceum, Fusarium graminearum, Fusarium oxysporum, Fusarium solani, and Fusarium sulphurem. The usual cause of this is very poorly aerated soil. Cold, wet soils are to be avoided when planting seedlings. Avoid overwatering, and avoid starting seedlings too early in the spring to avoid the cold. The product RootSheild, or any other fungi containing Trichoderma harzianum will also work. Agricultural farmers try to minimalize this by putting sodium nitrate in the soil after fall harvest, so it breaks down in the winter and turns into sodium and nitrate. Fusarium and Verticillium wilt & Charcoal Rot There is a conspiracy theory that these types of wilts were pursued by our government for biological control of outdoor marijuana crops. Fusarium and Verticillium wilts (along with Macrophomina phaseolina, aka charcoal rot) are most likley spread when there are insects in the ground, like broomrape or nematodes. Fusarium and Verticillium wilts are incorparated with tomatoes, peppers, and eggplant. On page 351 of the second edition of Greg Green's Grow Bible there is what i believe to be a good picture of fusarium wilt on cannabis. It is debatable, but I believe only a few varieties would be succeptable to fusarium wilt. It is best prevented by keeping invasive plants free from your grow area, and not letting soil pH to get below 6.5. There is no known chemical cure for these wilts. Rotating crops with corn is the only way farmers can keep charcoal rot growth to a minimal. It took me forever, but there it is. A huge list fungi cannabis can affect. I will come back and edit more as needed. Thanks GC and Happy Gardening! Thanks To the following websites, schools, books, and people for helping me create this article A review of Cannabis diseases List of causes of death by rate - Wikipedia, the free encyclopedia How Do I Recognize and Prevent Root Rot in Soil? | Michigan Medical Marijuana FAQ http://www.ct.gov/caes/lib/caes/doc...gy/septoria_leaf_spot_of_tomato_06-30-08r.pdf It http://www.nova-institut.de/secure/mcpartland-2-e.pdf Fusarium and Verticillium Wilts of Tomato, Potato, Pepper, and Eggplant, HYG-3122-96 Garden's Cure Cannabis Culture Forums Ed Rosenthal University of Minnesota The Marijuana Grower's Bible Second Edition by Greg Green Rollitup Forums Ohio State University
thanks! appreciate the feedback. i will update this frequently if i find new fungi, new information, or better pictures.
I had to read the whole thing after you diagnosed my babes with root rot.. so nice to see all this info (and pictures!) Put in one thread. Will def be coming back to this one again and again. Thank you sir!
PM doesnt like alkaline enviorments, and baking soda is an alkaline substance. use 1 tbs/gal of baking soda and spray down THOROUGHLY. dont use it again, because the salt in it (sodium bicarbonate) can harm your plants if used another time. if you are past week 2-3 in flowering (depending on how well the buds are devoloped), i wouldnt use it, as it can effect the way your finished product tastes.
Nice! Thanks dude, I noticed about 2.5" of Botrytis cinerea on the cola of my 5wk plant, and flipped! There isn't too much info on this on the web. Mine almost looked as if someone had dragged the cola through soil. Wierd! In my case, my temps were too cold, and humidity, too high. Thanks again for the info!......
fusarium wilt on cannabis is very rare. sorry, i do not have any more information to offer you on that subject at this time. creating a lacto-bacillus mixture is one of the best ways to prevent fungal growth. take a mason jar whole milk white rice flour sorry, im italian and measure everything by hand . so you have to just bear with me, because i dont use exact amounts lol. fill up the jar 1/4 of the way with white rice flour fill the rest nearly to the top with milk seal the mixture with the mason jar cap let it sit out at room temps for a few days. the milk will separate, and the top layer will be your lacto-bacillus. spray it directly on your plants (top layer only!) it will create an alkaline environment, its organic, and the bacteria will go to work for you! I appreciate the feedback again, guys! -OSUB