Plants that seem to attract more pests to the GH?
 

Hello all,

Every time I go into my greenhouse it seems to be a mixed bag of excitement and disappointment. Today, I ventured in for an expansive watering and found a new pest problem in addition to mites.

A new plant I recently brought into the greenhouse, a Cestrum nocturnum (night-blooming jasmine), was utterly blanketed in aphids. Every flower had at least 15 aphids. The plant was clean when I brought it into the greenhouse last month but has since developed the infestation.

Since they aphids liked this plant so much, this made me wonder if certain non-orchid plants are more likely to attract pests to my orchids?

It seems my citrus, my stephanotis, nor sambac jasmine (which was brutally attacked by mites this season but was fine for years) did not attract many pests but once I introduced a Gardenia and the Cestrum I got mites and aphids respectively.

Should I not have them cohabit? So far, the aphids were completely disinterested in all the other plants but I am not sure it will stay like that.

That said, the mites really decimated the foliage on my poor sambac and dendrobiums. I am particularly worried about the Sambac as the leaves are rather chlorotic now.

For better news, my Angranthes grandalena has a spike and my Miltoniopsis morris chestnut is blooming for the first time and looks great.

Yes, there are definitely plants that are magnets for pests. You are definitely not imagining it. I have seen this over and over with my own collection. Some plants are such favorites that the pests won't bother anything else while that particular plant is in the collection. My cinnamon tree has always had issues with soft scale but they like the cinnamon tree so much that they will cover every part of it (I keep washing the tree but the scale returns) and won't move to other plants.

Do you use pesticides on your plants? Malathion usually takes care of most of the problems you mention. For the plants you do not eat, you could use the granular Bayer 3-in-1 systemic. Then there is Neem oil. Or, you could go the predator bug route since you grow in a greenhouse.

For a particularly bad infestation on just a few plants, you could spray the plants with Olive oil in the evening and wash it off with soapy water the next morning. This is time consuming but very effective.

Good luck!

Definitely, the plants serve as food or snacks etc for animals (insects, snails, mites etc). I think if people were able to eat orchids, we would eat them too hehehe.

But - to protect our orchids from getting damaged, we really have to have options to prevent or cut down on the damage.

Imidacloprid can work nice (but bad for bees if there are any in the region). Oils sprays will help - but watch out for sun or heat build up, where oil on leaf surfaces during warm and sunny or very bright and warm conditions can lead to leaf damage.

I recently had spidermites attack one of my juvenile paphs. I sprayed "yates mancozeb fungicide plus miticide" (this is what this product item is called, or along those lines) ...... and it sorted out the problem very well. I have azamax, which I haven't used before, but will get around to using it in the future.

Dendrobium Wonga seems to be a beacon for scale on my shelves.
I keep it at the front so I can keep an eye on it.
It has made me wonder if these pest attracting plants are a good or bad thing.
As sacrifice plants they make you aware of pests as they are first to be chosen as a host, but the voice inside asks are they really beneficial as they do seem to attract these pests.

Remember also that you have no wind,rain, sun or birds to eliminate pests. You're totally under cover. People that own greenhouses are generally always scouting for pests.

Some plants have natural resistance against certain pests, others don't so yes there is certainly some that get affected more.
Then the health of the plant makes a difference too - they will pick the plant with the weakest defence.

Spider mites are the worst pest, I've had the red one and the grey one. The red one is really bad, had to use an industrial spray to get rid of them, the grey ones are killed with household neem oil and pyrethrin plant stray.

I use Bug Clear Ultra for most and it keeps them away. Is extremely effective against aphids.

One spray and the plant is protected for 3 months.

I think it is time you think about using pest spray. I don't like using it but if it's a choice between lush green leaves or my plant dying I will chose pesticides! No question these days. I don't eat my orchids either and haven't noticed any sideeffects.

OK, Mr. Stars. I’m going to pick on you now. (As an example. I’m saying this in a friendly, guiding way, so please don’t be offended. All of this is based upon my own, sometimes failed, experience.)

Yes, as has been said, different pests are more-, or less-attracted to some plants than others. The fact that you have issues with them is not, however, due to the presence of “attractor” plants, it is due to the fact that you are not doing a very good job at preventing their entry into the greenhouse, or controlling the ones that do.

Pests are a fact of life. Having a greenhouse environment means they have a nice, comfortable place to thrive. Preventive actions like quarantining or treating new plants before bringing them into the collection are far more critical when dealing with greenhouse growing, because of the favorable conditions as well as the more diverse “salad bar” you provide.

Unless you are OK with fighting bugs constantly, there are a number of things you can do besides such precautions.

Are the vents in the greenhouse open, or do they have screens to prevent easy access? In order to be properly qualified by the PA Dept of Ag for nursery cleanliness, I had to do that and even had to have a double door, providing an “air lock” to slow ingress to a degree.

Is the place kept clean and weed-free? Accumulated detritus on the floor or pockets of algae or moss can be great incubators.

Generally speaking, I think that, when growing in a greenhouse, you give away the ability to do spot treatments for pests. Sure, only the “sambac and dendrobiums have been decimated by spider mites”, but that does not mean they are not present on other plants. Spot treating is a temporary measure, at best.

If there is a pest, properly treat every square inch of plants, pots, benches, floor, etc.. Yeah, that can get expensive, but it’s all part of the price you pay to have a nice growing environment.

Believe me, throw some time, effort and cash into this now, and with a bit more focused care and procedures, your pest issues will be greatly diminished.

Ray, would you recommend bombing? I used to bomb periodically. I also used yellow sticky cards as whitefly indicators.

Indeed! I would like to know if bombing is a possibility. Couldn't one do that for an enclosed space regardless of it being a greenhouse? I'm thinking like maybe the BatCave...

Ray would be more up in this as my growing days were long ago. I remember we usually bombed overnight, so there was no venting. Then snuck in in the morning and turned the exhaust on. We had to wait awhile to go in. Then in later years we used a propane mosquito fogger. I'm sure by now Ray is cringing. But this was all ok with our nursery inspector (back then.) In fact, I often got compliments on the cleanliness...