Hey all.
I don't see a lot of info here on russet/broad mites (which may be a good thing if not many people have them) so I figured I would post my experience. First, go ahead and google what broad mite damage on cannabis looks like. Next, make sure you have a scope capable of at least 60x magnification. These things are tiny.
Ok, these are the worst pest I've ever encountered. They are so small that it is hard to notice them until they have caused significant damage. I would take spider mites any day over these things. The methods I use are 100% organic, so if you are the kind of grower who uses avid or the like in flower, or even veg, then just go to another thread.
On to the method...
VEGETATION:
This is simple. Wettable sulphur and soap. A product like safers 3 in 1 will work. Complete saturation is essential as is repeat applications.
FLOWER:
I had a tough time deciding how I was going to get rid of these things during flower. Some of my plants were six weeks in when I really discovered what was causing damage. First course is remove all infected material. That means cutting buds sometimes. The mites work their way up the plant from the bottom. I was going to give mighty wash a try because it totally destroys spider mites. However, it is expensive and I still don't like using a spray of any kind that late in flower. Some other treatments that I have used for spider mites in the past such as vacuuming them or blasting the plant with a hard stream of water had no effect on the broad mites. After much searching and wrangling my brain I came across a research paper talking about using heat to kill mites. Ladies and gentlemen, there you have it: HEAT.
These mites are sensitive to temperature and will die when the heat is raised above a certain threshold for a certain amount of time. The magic temperature seems to be between 120 and 130°. This was fairly easy to achieve in my growing space with four 600 W HPS lamps when I shut off all ventilation and closed every gap in the room. I raised the lamps after they weren't being ventilated to avoid burning the plant and added two space heaters. Within about 30 minutes I was above 120°. I left the plants there for two hours. The plants don't mind that high of a temperature at all. The next day most every single mite was dead. However, on some of the lower parts of the plant there was still some living mites. I realized that I hadn't lowered my thermometer to ground-level to find out if the heat was high enough all the way throughout the entire room. I repeated the process and for good measure left the plants in there for three hours. All the mites were dead. What I can assume is a good thing about this method is that it kills every mite in the room, not just on the plants. Heat also kills the eggs.
That's all there is to it. I hope none of you ever have to use this advice but if your plants are suffering from a mystery problem that you are chalking up to pH and nute issues perhaps get out the magnifier and pray you don't find a Russett mite. Hope this helps!
O
I don't see a lot of info here on russet/broad mites (which may be a good thing if not many people have them) so I figured I would post my experience. First, go ahead and google what broad mite damage on cannabis looks like. Next, make sure you have a scope capable of at least 60x magnification. These things are tiny.
Ok, these are the worst pest I've ever encountered. They are so small that it is hard to notice them until they have caused significant damage. I would take spider mites any day over these things. The methods I use are 100% organic, so if you are the kind of grower who uses avid or the like in flower, or even veg, then just go to another thread.
On to the method...
VEGETATION:
This is simple. Wettable sulphur and soap. A product like safers 3 in 1 will work. Complete saturation is essential as is repeat applications.
FLOWER:
I had a tough time deciding how I was going to get rid of these things during flower. Some of my plants were six weeks in when I really discovered what was causing damage. First course is remove all infected material. That means cutting buds sometimes. The mites work their way up the plant from the bottom. I was going to give mighty wash a try because it totally destroys spider mites. However, it is expensive and I still don't like using a spray of any kind that late in flower. Some other treatments that I have used for spider mites in the past such as vacuuming them or blasting the plant with a hard stream of water had no effect on the broad mites. After much searching and wrangling my brain I came across a research paper talking about using heat to kill mites. Ladies and gentlemen, there you have it: HEAT.
These mites are sensitive to temperature and will die when the heat is raised above a certain threshold for a certain amount of time. The magic temperature seems to be between 120 and 130°. This was fairly easy to achieve in my growing space with four 600 W HPS lamps when I shut off all ventilation and closed every gap in the room. I raised the lamps after they weren't being ventilated to avoid burning the plant and added two space heaters. Within about 30 minutes I was above 120°. I left the plants there for two hours. The plants don't mind that high of a temperature at all. The next day most every single mite was dead. However, on some of the lower parts of the plant there was still some living mites. I realized that I hadn't lowered my thermometer to ground-level to find out if the heat was high enough all the way throughout the entire room. I repeated the process and for good measure left the plants in there for three hours. All the mites were dead. What I can assume is a good thing about this method is that it kills every mite in the room, not just on the plants. Heat also kills the eggs.
That's all there is to it. I hope none of you ever have to use this advice but if your plants are suffering from a mystery problem that you are chalking up to pH and nute issues perhaps get out the magnifier and pray you don't find a Russett mite. Hope this helps!
O
