Gnats in the GH???

I have a bad case of fungus gnats in the house, I have sprayed everything I have growing, so I am hopeful everything will be okay. My question is, I just potted up a bunch of lily bulbs I received out in the GH. While I was out there today, I noticed gnats out there. Should I spray the soil on those pots? I am really new to treating things from all these pest and such. The spray I have is from Schultz and is for house & garden plants. Fungus gnats is listed as one of the things it kills along with the eggs.

Thanks Connie

Connie, the best thing I've tried for them has been sprinkling a layer of crushed granite (chick grit from a feed store) over the surface of the soil. Diatomaceous earth can be used too, but I found the crushed granite to be just as effective and much cheaper. As I understand it, the soft bodied larvae can't survive the sharp edges of the granite.

This year I've got them again, but there's too much growing in the plant room to deal with. At least they're localized to that room only; last year at my old house I had them everywhere in the house- drove me nuts! They don't appear to harm anything, but I have been hitting the soil surface when I'm spraying Neem oil and that seems to keep the numbers under control.

Connie
I don't know if this will help you but it did say all houseplants scrolls down the page to Gants and there is some information on gants I hope this will help
www.optimara.com I grow alot of indoor plants most are African Violets but it may help
Dimmer(AKA) Kim
I look on this you need to go toon Home page and go to Pest and Pathogens than to Gants Fungus Sorry about that I wood have copy and paste but I didn't know if you can do that

This message was edited Mar 21, 2008 7:46 AM

Thanks gemini &Dimmer that article was good :o)

Thanks again, Connie

There is very little you can do to kill them. They don't harm plants very much. The adults are quite resilient to chemical spray. Instead of spraying the adults as I have done in the past months, I now vacuum them up :*) I blow gently on the lily seedlings and suck-um up when they go scurrying.

Well they are causing a lot of trouble for my poor babies, the eggs are hatching and eating the roots, a friend of mine lost all of her day lily babies from the larvaes,
I haven't seen any adult ones since I sprayed, but there sure is alot of baby ones :( and they are a pain in the ***.
I just ordered some knock out, and hope and pray it gets here b4 I lose all my seedlings, my tomato & pepper plants are doing ok since I put sevin dust on them, but I don't want to use that on my flowering plants. Just about all my impatiens are gone and now my red spider zinnias are dying :(

I don't know if lily roots are different from daylily roots but fungus gnat larvae eat those and kill the plants. The adults don't do anything except lay the eggs that hatch the larvae. It could be that lily roots are immune to this kind of damage. I did see some articles saying they weren't doing any harm to lilies but didn't know what that was based on.
I know those larvae are a threat to the roots of other types of plants too.

MollyD

Thank goodness many things go unharmed, or I'd be in a world of trouble! Tiny seedlings would be most at risk. Increased air circulation (by fan) seems to have helped with mine. Does that make any sense?

They tend to eat decomposing plant matter in the dirt. If the dirt dries out a lot the larvae are more likely to seek out the roots. So I have read...

This message was edited Apr 1, 2008 8:05 AM

Ya Neal that does kinda make sense :o) Will have to get dh to get the fan out and give that a try. I need to start a fan anyway and start the hardening off process. I am going to start putting them on the front deck during the day, here in a couple of weeks. April/May has really been strange here in Mi the past couple years, so I have to be really careful.

Thanks for all the info. you all have been a great help :o)

Connie

It almost seems as though the information out there varies by the plants the writer is familiar with! Here is what Wikipedia says about them http://en.wikipedia.org/wiki/Fungus_gnat


MollyD

Thanks Molly, I had read that article too. I was bottom watering and stopped that, and it does seem to help some.

I currently have about 1000 daylily seedlings in my greenhouse. All plants are allowed to dry thoroughly to a depth of 1" before they're watered again. Guess what I've got? Gnats. They really don't seem to care if the soil is wet or dry. They're very destructive (in their larvae stage) to my seedlings' roots. It's a constant battle to keep the plants alive and growing.

MollyD

There is a professional drench that contains bacteria that attacks the larvae, but it is quite pricey.

intercessor,

Used it last year. Didn't wipe them out. It only slowed them down enough for the plants to make some good growth.

MollyD

My day lilies are doing ok, it was my friends dl's that they destroyed, I let my plants dry out in between watering.

I do have a question about the dl's tho, I sprayed all of them with messenger and now some of the leaves are now turning brown, I know it can't be the messenger cause I used it before (last year) could it be I am not watering them enough???

Thanks in advance, Connie

Connie mine have leaves turning brown but that's what the gnats do. As they eat the roots the plant looses one leaf after another till it dies completely.
Are yours in your house or outside? Inside the house they can get very dry and turn brown.

MollyD

Mine are in the house for now, I will be putting everything out in the gh in a couple of weeks. I only have an electric heater to run at night out there, so to keep the cost of the electric down I have to wait. I insulated around the base of the gh, but I am going to put some plastic over the window areas to help at night.

Molly when it's the gnats causing them to die out, do they start to turn brown from the tip down, or from the base up? Mine are turning brown from the tip down :( I trim them and then feel to see if they need a drink. I hope and pray I don't lose them, they are all started from seeds I have received from various members here on daves.

Pepsi mine turn brown from the tips down. I don't know if you can see them in this picture from my greenhouse but there is a lot of this kind of damage going on.

MollyD

Wow I thought I had a lot of plants started rofl
I could barely see them, I am half tempted to go buy enough cups to put them all in water. my granddaughter picked out 7 of the dl babies that were growing and I just have them in water and they are thriving.... Doing alot better than the ones in dirt.

Is your gh heated? I was just wondering when I put the heavy plastic up to cover the windows in mine, if I would need to run the electric heater at night.

It is heated. We get temperatures of -20 bad winters, -5 most winters and as soon as there is no sunlight the temperature in there drops like a lead baloon. In the dead of winter it's heated 24/7. This time of year I can run the heat just at night most days.

There are about 1000 in there. This is my first year doing the cups. I'm not happy with the results. Normally I use 1 gallon pots. The growth in the cups is much slower. I used them this year because I ran out of space for the bigger pots. We're getting a new greenhouse this summer so we should be able to go back to the pots for next year. There are tacks behind the one you can see and another rack just to the left from where I'm standing. Also shelves running across the back and along the right hand side. The greenhouse is 8'wide x 17 ft long x 7.5' high.

MollyD

Do you use a propane heater to heat with? That is what I am wanting to get for this coming winter, but gonna have to really save to get it...

The pic is my gh, as you can see not very insulated with those windows, I do have the base of it insulated and figured I could put the heavy plastic around the inside of the windows except the vented windows. and run my elec heater at night, during the day the temp is right around 80/90 but it drops fast with the night temps... I haven't gotten around to it yet but I want to add some more shelves to hold more of my trays along the windows. My gh is 10x12

It's very pretty Pepsi!

What I would do to insulate it is buy bubblewrap at one of the greenhouse places online. Charlie's Greenhouse is pretty good. I've dealt with them several times http://www.charleysgreenhouse.com/index.cfm?searchflag=1&page=_search&s=bubblewrap&PageNum_newsearchQuery=1&varShowPer_custom=12&varOrderby=ProductId&varSorting=ASC&varColumns=3&f=1&enter.x=16&enter.y=16&mtype=3

In my greenhouse I used a clear solar pool cover to insulate. Does the same job but was more expensive so next time I'm going with the bubblewrap.

I use different things to heat depending on the weather. In the fall when it's still mild I used an electric heater. During the winter I added a kerosene heater (10K btu) in addition to the electric heater. You need to research kerosene for your plants because some don't do well with it (like tomatoes) while others like daylilies don't care. Right now I'm running a small propane heater (the kind you clip on the top of a 20# tank) I've used a full size 20K btu propane heater in there but it kept using up all the available oxygen and snuffing out usually at night so I gave up on it. You need to research prices in your area to figure what's the least expensive way to heat too.

MollyD

Electric is so expensive :*( Just running my 4 florescent lights in the basement and a space heater cost an extra 20-30 a month.
I read an article where water jugs were used to absorb sun light and at night the heat would keep the greenhouse above freezing.

intercessor I have 4 drums (55gallons each) painted black and filled with water. Hasn't made the least difference. Someone over on the greenhouse forum did a test using different amounts of black paint, kinds of paint (glossy vs flat) and no paint. Results showed no real heat gain from any of them.

MollyD

I used 2 gallon watering cans with 1/8th of a mosquito dunk in them to water when those little buggers showed up, and it took care of them. It is the same bacillis.

Yellow whitefly traps worked too. I hung then near the florescent lights. I have a lot of plants that spend the Spring, Summer and Fall outside, but winter inside so gnats have been a problem when I bring them in. When the first (and only) hatch came last fall in the basement they covered the traps, but we're talking about a lot of plants.

Between the 2 methods ther have been upstairs.

DH and I just got back from Lowes, and there was a gal there that said I should use dish soap in my water and give all my plants a drink, she said it sufficates the eggs and hatchlings, she swore it works, I am gonna try that on my dl's and see if it helps, my knock out won't be here for about a week. I don't think it can hurt them... I have use dish soap and sprayed some of the plants outside and it worked great, but never used it to water the plants...

Tried the mosquito dunks, tried the dish detergent, Nothing. None of them worked to keep the gnats away or just die off.
The only thing that seems to work for a few days is Schultz's insect spray but after 3 or 4 days they come back. That stuff is $4.50/pt so with this many plants it gets very expensive very fast!
Next year I'm going to try Olympic Marathon systemic. Pricey but you only use it when you put the seedlings into their pots. We'll see if that does the trick.

MollyD

Molly, notmartha is the one that told me about the Knock Out, you can only get it at Gardens Alive, http://www.gardensalive.com/product.asp?pn=1962 its 20 bucks and she swears by it. I have some coming but like I said it will be at least a week, its been shipped, got the confirmation, just not sure when I will see it.

I used the Schultz's and it did kill all the adults, but my oh my the babies that are hatching :( I just bought some more potting mix and if the dishsoap don't help I will have to wash each one of my babies and try repotting them... this is really discouraging. I have some really cool DL babies and I just hope I can save them.

Did the Knockout last year. As long as I was pouring the stuff on they died back. As soon as I ran out they came right back. My new greenhouse is going to have a cement floor. Just in case the dirt floor houses any of these buggers. This greenhouse will become a henhouse in June.

MollyD

The soil good be sterilized in an oven for an hour at @ 275-300. That would at least kill any eggs that come with the soil. Judging from the amount of dirt you have though, that may be impractical.

LOL I go through about 4 or 5 bales of Pro-Mix. Would need a professional pizza oven to do it in under a week! Thanks for the thought though.

MollyD

I stuck some in the micro wave and it caught on fire, my dad told me to stick the dirt in the freezer, I laughed and said why not, I got plants in the fridge :o) Should of heard dh when he opened the fridge door and seen what was in there lol... Not sure freezing helps kill the eggs or not, sure don't seem like it would considering our weather conditions.

Most of the bales I get in winter are solid frozen blocks you can't even chip into. Never hurts anything in them.

MollyD