Hi everyone just a quick question..I have those little black flies buzzin around on my cocoa and I have also seen the larvae an inch under the cocoa. I have just laid out several yellow,blue sticky traps which is catching several of them but I'm more worried about the larvae and was wondering if its worth buying some something like gnat off or anything with Bt in it? I'm not being stingy but I'm just over 6 weeks into flower and only have another 1 and a half weeks until harvest + my plants are extremely healthy and don't seem bothered?? I'v also read on other forums that they don't really harm the plants unless the plant is already poorely....any thoughts??
The larva can be an issue to the root system but I think the larger issue is that the gnats are fungus farmers. They carry spores on their legs (like bees and pollen) and they grow the mold on your buds. So knocking this down now could very well save your plants from a possible infection. Sticky traps is a good start. I think your best option is to use diatomaceous earth on top of the coco. Use about 2cm of the stuff as a top dressing and it will act like shards of glass the flys have to climb through to lay their eggs an escape from the media. The shards cut them up and they bleed out and die. There's no spraying, no pesticides, and it will take care of new gnats as they arrive. Better to be safe and spend a couple of buck on some diatomaceous earth than to lose your crop to a mold infection.
SCMC thanx for quick reply i have tried to buy some diatomaceous earth but struggling to find it in the uk I'm getting the same blank looks I got when I asked for mosquito dunks..lol.. not many of them around in these parts. So I have got some potato slices for the larvae and more sticky traps as the bloke at the hydro store said not worth buying gnat off as so far into flower..which is weird as they usually want the pound note. lol
Hey Goldenbrown I have a remedy for you. Trust me you don't want gnats to get out of hand, they'll eventually get stuck in your buds and you could spend hours tweezing them out. Get some predatory mites, Hypoapsis Miles to be exact. I tried Diatamaceous Earth with no sucess along with Pyrethrum drenches, sticky traps, etc. Just sprinkle the mites on top of wet coco and they will go to work searching out and eating the gnat larvae. You have to stop the larvae to stop the gnats. Still use the sticky traps to catch the adult gnats flying around. The best thing about these mites is you can apply them right up to harvest, let nature take care of it for you. They're microscopic, I could barely see them with a 30X lens. Mine came in a canister that they could stay alive for 2 weeks if kept cool and dark. So I saved some and re-applied after 1 week and again after 2 weeks. Completely wiped out my infestation, haven't seen a gnat in over a month now. Here's a bunch of stuff I found on 'em... Hypoapsis Miles Release these mites at sundown within 2 weeks of arrival, the sooner the better (please note storage requirements below). Water the medium or soil no sooner than ten minutes before releasing these mites and wait a couple of hours before watering after the release. To release, gently rotate the shaker canister to distribute the mites evenly within the carrier. Next, open the screw top in the crop area, remove the filter paper, re-secure the screw top and gently tap them out of the shaker canister through the small holes evenly onto the slightly damp growing medium or soil or Shiitake “logs.” These mites should also be released onto dirt and gravel floors, around greenhouse weeds, under benches and ground covers, and any place fungus gnat larvae and pupae or thrips’ pupae and pre-pupae may develop. Concentrate the bulk of them at release points near the most heavily infested or most active breeding areas. Leave the shaker canister and filter paper in the treatment area for 24 hours after release to ensure all mites have exited, unless a small area is being treated, in which case the cap should be re-secured in order to store the balance of the mites for the next release. Do not store the mites in the shaker canister for more than 2 weeks. Hold at a very humid 60-70F. It is best to store these canisters on their side (this provides more surface area for the mites within the confines of the unit). This tiny (0.5 mm) light-brown mite naturally inhabits the top 1/2" layer of soil where fungus gnats, as well as springtails and thrips pupae dwell. The female Hypoaspis mites lay their eggs in the soil, which hatch in 1-2 days, and the nymphs and adults feed on the soil-dwelling pests. Populations of Hypoaspis include both sexes, but the males are much smaller and rarely seen. Each Hypoaspis mite will consume 1-5 prey or eggs per day. They survive by feeding on algae and/or plant debris when insects aren't available. Their entire life cycle is 7-11 days. Hypoaspis are used primarily for control of fungus gnat larvae, but they also feed on western flower thrips pupae. Hypoaspis can also be effective at ridding pet tarantulas, lizards and snakes of pest mites. Moisten area before introducing Hypoaspis. Introduce a few tablespoons of substrate with hypoaspis per habitat every day, as needed. Pest mites should dissappear within 48 hours. Continue introducing Hypoaspis until container is empty. Lighter dosages serve as a preventative, higher dosages as a curative. Release rates: 5,000 mites treats 500-1,000 plants; 10,000-25,000/per acre. For maximum fungus gnat control, use with Neoseiulus cucumeris and Beneficial Nematodes. Application: Hypoaspis should be released immediately upon arrival. Moisten soil or target area planting media at least 10 minutes prior to release. Containers include a shaker lid which allows for distribution over the soil surface. Concentrate the bulk on the most heavily infested areas. Hypoaspis moves well on soil surfaces, so it is unnecessary to apply to all surfaces. Leave the empty container in the treatment area until any stragglers have left. Although Hypoaspis will move between plants in pots, at least every second plant should be treated. Application needs to be made early enough to allow the mites to spread. They will not move throughout an entire greenhouse from a single introduction point. Hypoaspis will not survive below the top 1/2 inch of soil, so mixing mites into the growing media prior to potting is not recommended. Other biocontrol agents to use in conjunction with Hypoaspis are Ladybird beetles, Green Lacewing, Minute Pirate Bug (Orius sp.), and Neoseiulus cucumeris, Beneficial Nematodes (Steinernema feltiae), and Bacillus thuringiensis var. israelensis.