Greenhouse Scout School 2026

Hi everyone,
1. Sticky card #1 on Peperomia = one fungus gnat adult on yellow side; nothing on blue side
2. Sticky card #2 on Maranta (prayer plant) = one fungus gnat adult on yellow side; one fungus gnat adult on blue side
3. I think there were not more pests for these reasons:
Too much overhead watering with a wand may have damaged some of the pests because I thought maybe I saw a pair of legs but no body a few times.
Not that many pests in the greenhouse because the managers reported that they don’t usually have huge problems with insect pests.
I had to place the cards in less-than-perfect locations because I had to respect the owner’s request to not make the cards very visible since his customers have often equated one pest sighting with “full-blown” infestation, so this visual can be a negative marketing issue for him.
4. Potato on two house plants in main greenhouse:
One potato was accidentally moved and discarded by a greenhouse worker, so I got no results.
One potato accidentally left the building with the plant when a customer purchased it, so I hope there were no fungus gnat larvae in it!! Ironically, one of the managers and I specifically selected that plant for the potato experiment because it was the least likely one to get purchased.
5. Potato on venus fly trap in separate area of the greenhouse used for recovering plants:
I definitely saw a fungus gnat larva with a black head while examining it with the Optivisor. When I tried to find it with the handheld lens, I could not see it. The potato was very “spent” by then because I waited a few days to check it.
I then found a larva but it does not have a black head, unless the head is pointing down and not visible from this viewpoint.
I also think I found a carcass of a fungus gnat larva.
Also, can you see the black item circled in one of the other pictures? Is that an aphid mummy or carcass?
And… I saw an insect running around and tried for a long time to get a clear picture, but could not. So, I took a series of pictures and then used Clipchamp to make a video to show the path I saw it take.
6. New things learned with technology:
I used “markup” in the picture editing options to put red circles around the insects.
I tried Clipchamp to make a video by linking several still shots together in the video editing app.
7. Things to do differently next time:
Check the potato after one day.
Bring a phone charger because the handheld scope seems to use a lot of juice.
Ask the current greenhouse worker to tell the next greenhouse worker about my sticky card and potato placements. I think I have now met everyone who waters and helps customers in that greenhouse, but there are many front-end cashiers, and I have not met them all yet, so there is still a chance that a customer will walk out with one of my test plants. The plants were all very clearly marked with flags and wording indicating that they were part of an experiment.
8. I have added new sticky cards in a different area where I saw an insect fly by.
9. I added new potatoes where I last saw the fungus gnat larva on the previous potato.
10. I will comment under my own post here to later add the information about the plant we are supposed to research. I am doing Livistona (Chinese fan palm).

Have a great week, everyone!
Amy Howansky

A Few Pests and Diseases in Geranium Plants
Prior to this course, the only pests I had to deal with on geraniums have been mammals nipping buds, raccoons tipping pots, and a June beetle infestation in the summer. However, overwintering geraniums inside in a greenhouse setting has delivered an entire new set of challenges.

 
My main problem working indoors with geraniums has been the various root roots which we have talked about in class. With the new information I have gathered from the course, I believe my main issue is using field soil and old pots, which carry fungal spores and bacteria.

 
Pythium stem rot (also known as ‘Blackleg’) is a disease caused by the fungus Pythium. This fungus causes rapid death of the plant as it starts from the base of the stem at the soil line. This causes the plant to collapse and die. Roots become rotted and lose their outer layers. This fungus favors wet soils and spreads through contaminated tools, soil, water and pots.

 
Another type of root rot is bacteria driven. Bacterial blight, caused by Xanthomonas campestris pv. Pelargonii, can cause water-soaked spots under the leaves. This is followed by brown/yellow V-shaped. The first sign of disease is usually seen on lower leaves. Eventually, this can progress to stem tissues, causing them to become dark and rotted.

From the research I did, preventative maintenance is key. To prevent this fungus or bacterium from taking ahold of your geraniums, destroy infected plants and their soil immediately to prevent their spread. Always clean pots and tools with a bleach solution after use, and use well-draining, sterile soil for overwintering.

 
The last pest I did research on were Geranium Budworms. I found that these are generally a garden pest, but they can pop up in greenhouses given the correct conditions. These caterpillars consume the buds and petals of geraniums (as well as petunias). Doing so, prevents the flower from opening. Monitor for this pest by checking flowers and buds for small holes. They are more active during dusk, but you can still see them during the day if you look towards the base of the plant.
Sources:
(https://yardandgarden.extension.iastate.edu/article/1995/8-25-1995/gerphy.html)
( https://yardandgarden.extension.iastate.edu/article/2006/3-8/geranium.html#:~:text=Bacterial%20blight%20and%20Southern%20bacterial,is%20free%20of%20the%20pathogen. )
(Budworm - Petunia Calibrachoa, Geranium : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst)

To finish the assignment, I chose to research Livistona.

Livistona (Chinese fan palm) is a tropical house plant, but in the wild it can grow 10-30 feet tall. It prefers moist soil and full sun. The large palm fronds have a characteristic droop when they are mature.

A common pest of Livistona is spider mite because they favor the hot, dry environments that can occur in a house during the winter when the air is dry and hot from heating units. Scale insects also cause issues because they suck juices from the stems. Scale appear as small, round bumps, which don’t actually look like live creatures. Mealybugs also pierce the plant tissue and suck the sap. They are usually hiding in plant crevices, and look like tiny pieces of white fuzz. Mealybugs excrete honeydew, which can then support the growth of sooty mold.

Aphids are also piercing/sucking problems, and can cluster on new growth. The damage appears as yellowing and curling of the leaves. Thrips damage the fan palm by leaving “scratches” on the plant tissue surfaces. Whiteflies and fungus gnats are also common pests.

I talked with the greenhouse manager where I am scouting, and she said, “Basically everything bothers them. They are a pain to manage.” When I asked her why, then, does the company bother selling them, she said what is clear to see: they are dramatic and beautiful, and customers love them.

Citation: https://cafeplanta.com/blogs/resources/chinese-fan-palm-pests

Week 3- Here are a few pics, the video is of fungus gnat larvae crawling around on the potatoe slice I placed in a potted colea cutting. I did not see a significant differnece from blue to yellow with Thrips and the card that showed the most thrips was laterally placed to catch fungus gnats more and in pots with Boston fern in them. We have had a problem with thrips in our greenhouse for the past two seasons.

Nothing exciting to report. I had my blue/yellow sticky card out for a week and I only caught one thing - some sort of wasp, possibly one of our Encarsia formosa's that I released in December. We had some thrip in our streptocarpella but I can't find any anymore, I guess that's a good thing! Looking forward to tonight's session!

Hello!

My traps have not been out for a week yet, but I did find some mites on one of my potatoes, and I'm not sure what they are. I don't have anything in the photos for scale (and they are a little blurry - still getting used to the microscope) but they are probably about a millimeter long.

Hi All,
1) Not really too much to report for the sticky cards. My cards had a majority fungus gnats with some shore flies and a few good guys because I release colemani preventatively. I recently did an application of nematodes so it will be interesting to see if my fungus gnat numbers go down because I uncovered the reverse side of the card.
2) I did have some fungus gnat larvae on my potato wedge but I also had a longer worm/larva looking creature that didn't look like a fungus gnat larva to me. I've posted two videos below. I also have what I assume are springtails.
3) We've started our 1st pepper succession and like clockwork the aphids have found it. It is amazing how much aphids like pepper plants. I suppose this would make peppers a good sentinel plant to see if my pest management practices are working?
       

  

1. I found two kinds of insects on the sticky card. I found 13 shoreflies and 32 fungus gnats. There were much more of both insects stuck on the yellow side than the blue side. I could not see any other kinds of insects.

2. I set 4 potato wedges in four separate containers within the same crop. Of the four, I found one fungus gnat larvae underneath one of the potatoes. The one that was found had the most moisture in the soil. I was dark and moist to the touch, but the other three wedges were dryer and no fungus gnat larvae were found. 

3. The plants growing in the containers where I put the potato wedges are lavender plants. While lavender is generally considered pretty pest and disease resistant, here in the south (North Carolina), where it stays pretty humid most of the year, lavender are known to succumb to root and crown rot caused by phytophthora. I have also seen small white caterpillars eating on the foliage on some of the cultivars in this same greenhouse. In my experience so far, I haven't seen anything else affecting the lavender. 

My potato wedges from week 2 didn't show any fungus gnat larvae. They looked like they had dried out, so I will try placing wedges in a few other plant varieties to see if anything appears. I placed the blue sticky trap in a Lickety Split philodendron (the last shipment we received of these plants had thrips), but I haven't seen any thing yet on the trap. I practiced taking pictures of fungus gnats on a different sticky trap.

I've attached photos of problems I discovered while scouting. I believe the sago palm has scale, the hoya and ficus lyrata have spider mites and I'm unsure of what's going on with the white wizard philodendron. The black spots look like evidence of thrips, but it's so consistent (just on the necrotic tissue) I don't think it is. Advice welcome!

We've had problems in the past with mealy bug on hoyas and root rot. Upon further research these plants are also susceptible to spider mites and scale.

The potato wedges have not yielded any fungus gnat larvae this week. The numbers on the sticky traps are still remarkably low since treating with nematodes. I've been seeing some fruit flies on the traps.

I appologze for late post I had thought I had already put the numbers in! For this greenhouse trap one had:
1 thrip
4 fungus gnats
2 parasitic wasps
And 2 house flies
Trap 2 had:
2 thrips
1 fungus gnat
1 shore fly
Trap 3 had:
2 white flies
5 thrips
3 fungus gnats
1 shore fly
At the time there wasn't ,any plants in this greenhouse, and the few plants we did have were still fairly young. At the moment though, that's another story!
The crop I chose are the super Olympia begonias. I am already conducting my own little experiment on them anyway. I have them split up to were some are getting more heat and moister and the others are getting less water and cooler temps. The ones that's taking moister are having a fungus gnat problem but that was to be expected. What is surprising is the ones that are getting more water and heat are suffering from a few different nutrients deficiencies but are growing better despite it. The ones that are cooler and away from the Texas sun, are starting to get root rot and fungus gnats are also present. I changed the potato over to the begonias and discarded the old ones. The old ones were clean and showed no signs of larvae.