Category Archives: Insects Abound!
Troubles in Vine-Land
As I mentioned in passing on Tuesday, we have several different things going on with our vining vegetables – cucumbers, squash, etc. Actually, the melon plants are all still in good shape, so the problems are restricted to the cucumbers and various squashes.
Here’s the first one:
The cucumbers in the Family of 4 Garden are coated with these…any ideas? I’ve seen numerous samples of vine plants come in this month with the same signs and symptoms. I think what tricks folks is all of the white flecks. This is actually a severe aphid infestation. If you look closely, especially in the upper left corner of the picture, you can see the green buggers. In the middle of this picture is an ant…and ants like to “farm” aphids and protect them from predators so the ants can feed on the sticky honeydew that the aphids excrete as they feed. The white flecks? Those are the aphid “skins” as they grow and mature they “molt” and leave those white skins behind. I’m sure there’s a technical term, but I can’t remember off the top of my head.
To make matters worse, the cucumbers also have these terrible looking insects on them! Can it get any worse? Well, actually, you might recognize the one as a ladybug, and the black and orange lizard-like bug…that’s the larvae of the ladybug! These are the good guys that are enjoying quite a feast of aphids!
So, what are we doing about the aphids on the cucumbers? Well, honestly, the answer is nothing. We’ve gotten quite a bounty of cucumbers, and the plants are still doing pretty well overall. The ladybugs aren’t controlling the aphids at this point, although given a couple of weeks they might get there. Spraying would kill the ladybugs and may not do much to prolong the life of the cucumber vines. We’ll probably let them go and pull the plants out in a few weeks if they become completely unproductive.
On to the next problem… An observant Master Gardeners saw this on the underside of one of the squash leaves on Tuesday. Theses are squash bug eggs. I’ve gotten several questions about why we aren’t having problems with squash bugs in the garden this year. The answer has pretty much been that we’ve been lucky. The renovated garden may have helped that situation too. At this point, we aren’t going to bother spraying, since most of the squash will be leaving the garden soon due to the third problem we’re seeing…
Ugh…powdery mildew. This is a disease that we often see on zinnias and other common garden plants about this time of year. Usually you start out seeing round, powdery white spots on the leaves. It seems like most of our squash went from 0 to 60 in almost no time flat, because the leaves are pretty well coated on several different varieties of squash. There are treatment options, but they are most effective as preventatives or very early in the infection period. These plants just aren’t worth saving at this point. Besides, we’re tired of zucchini! There are powdery mildew resistant varieties, but they can still get the disease in a bad year.
As you can see, a lot of things are starting to go downhill fast in the garden this year. Luckily we’ve got some seeds started inside and garlic on order for later this fall!
Eggplant Lacebug
On Tuesday, while we were out working in the garden, one of the Master Gardeners noticed that the ‘White Egg’ Eggplant had some leaves that were looking a little speckled. We checked the undersides of the leaves, expecting spider mites, and this is what we found:
At first glance, it looks like a bunch of aphids with a weird fly thing hanging out with them. The bizarre part was that the winged insect didn’t fly off when the leaf was disturbed.
After some keen eyes and a little research by one of our afternoon Master Gardener Hotline workers, it was determined to be a lacebug. I looked in the Insects of Kansas book and found that there is actually an Eggplant Lacebug. It said that the adult lacebugs will hover and protect the eggs and nymphs, which is exactly what the adult lacebug appeared to be doing on our sample. Lacebugs, as Hemipterans (true bugs), feed by piercing the leaves and sucking the juice out of them, very similar to how aphids and spider mites feed.
The Insects in Kansas book calls these a “frequent pest of eggplant,” but it is certainly a pest I’ve never seen before!
Wilting Squash Vines…Well, That’s a Bad Sign!
I took a bunch of pictures of all the of vine plants this morning to take an early season tour through the Vertical Garden, and everything was looking pretty good, for the most part. Then I stepped out of the office for a couple minutes this afternoon to take a break from the new carpet & glue fumes, and noticed this…
**Sigh**. Seriously?!?! Looking at this wilty squash plant (It’s the ‘Sunshine’ Kabocha, in case you’re interested), there were 3 possible problems. 1 – the plant needs water. Nope, the soil was moist. Darn…that’s the easy fix! 2 – That pesky overwatered & damaged the roots problem. Well, theoretically possible, but we’ve been pretty careful recently, and it has been plenty hot to keep things from staying too wet very long. 3 – Squash Vine Borers have attacked. We have been scouting, but that’s not perfect.
So, I checked out the base of the plant for signs of invaders.
I realize it is kind of hard to see in this picture, but there are the few spots where you can see the orange goo oozing out. That is textbook squash vine borer damage. GRR! I was so hoping we wouldn’t have any this year due to the fresh soil… Oh well, I guess I can be overly optimistic at times if I want to be. Not that it’s a good way to keep plants healthy, but it’s fun while it lasts.
So, what do we do from here? Well, the catch with squash vine borer is that once it is at this point – inside the plants – there isn’t really much to do about it. Some people have good luck with surgery – going in with a knife and extracting the caterpillar, then mounding soil over the wound and hope it puts down some roots and keeps growing. Since our plantings were relatively thick to start with (more plants than we needed), I’m tempted to cut this plant out and spray any other plants, in hopes that we aren’t too late to prevent further loss.
For anyone that has never had the pleasure of dealing with squash vine borer, the only way to kill the caterpillars is to spray the base of the plants regularly with an insecticide in hopes of killing the caterpillars before they bore into the stems. Sevin or Permethrin would be conventional options. Spinosad would be an organic option.
I hope we’re not too late to catch most of the critters, because we have a LOT of squash planted in the garden this year!
Friday PhotoEssay
I think we’ll call this week’s Friday PhotoEssay the “Death & Destruction” Edition. I was out of state since last week, and then was welcomed back home on Wednesday with a lovely hailstorm. Luckily, the garden doesn’t look much the worse for wear due to hail. Unluckily, there are a few things going on that are probably due to the learning curve with our new garden and not much we can do about it.
This pepper plant (and some of the others) are showing this stunted, distorted new growth. I think there are two possibilities – either herbicide injury (we’ll discuss that in a bit), or thrips. We had thrips like crazy last year, but it doesn’t look quite the same to my eye.
Here is a bean in the “Beautiful Vegetable” Garden that is showing similar stunted, distorted new growth. Hmm…I’m sensing a pattern here…
The Black Sesame seedlings are still pretty tiny, but actually looking quite good, comparatively.
I think this is the second planting of this ‘White Egg’ Eggplant, and this plant is already getting heavily chewed. I saw another pesky cucumber beetle on it. For some reason they are leaving the cucumbers alone so far and attacking the eggplant. (Not that I particularly mind that!)
The French Marigolds are looking nice in the Edible Flower garden, even if not particularly tasty.
This one isn’t nearly as difficult to diagnose with certainty as the pepper and bean above. This tomato is showing very clear signs of phenoxy herbicide damage. The most common herbicide that causes this injury is 2,4-D. UGH! If the damage isn’t very severe, the plants usually recover from it. If the damage is quite severe, the plant will remain stunted and have much reduced yields. Most of our tomato plants are showing this damage, which isn’t surprising as they are some of the most susceptible plants. (Grapes and redbuds are also highly susceptible.) I can’t tell yet how bad the damage is. The question is…where did it come from?
To be clear, I also suspect that the peppers and beans showing symptoms also have the phenoxy injury.
This squash plant is also showing some slight distortion to the leaves and veins. I would say the squash, melons, and cucumbers are the least affected, with more variation between varieties.
So, where did the herbicide damage come from? 2,4-D herbicide injury is very common on garden plants in the spring in Kansas because it is widely used to treat dandelions and other broadleaf weeds in lawns as well as broadleaf weeds in corn fields or other crops. It is very easily volatilized, which means it can get on the wind and blow for long distances, especially if someone sprays the herbicide on a day with wind. (Just as an aside, if you really want to control dandelions, you are better off spraying in the late fall rather than in the spring when you see them bloom.)
However, we’ve never really experienced herbicide damage in our garden and we don’t use 2,4-D on our grounds in the spring. It is possible it came from somewhere else nearby. I’m also wondering if there is some other herbicide residues in the compost we got… It is theoretically possible that there was some type of herbicide residue in the feed or bedding the horses used that was not completely broken down during the composting process. If that is the case, there really isn’t anything we can do about it. Most herbicides should be completely dissipated by 1 year later.
It looks like we’re in for a rough gardening year, even if the weather continues to cooperate!
First Insect Pest of the Year
We planted on Tuesday and yesterday morning when I was out in the garden I noticed a few munched on leaves…as well as the culprit:
A dastardly cucumber beetle! Rather, there were several beetles on several different plants. Normally sighting a single beetle on a plant would not trigger the need for spraying. However, on young transplants and seedlings, cucumber beetles can quickly devour the whole plant. I believe that 1 beetle per plant is in fact the “economic threshold” that triggers spraying. (“Economic threshold” is a term for the population level of insects at which there is likely to be an economic loss if treatment is not done. Determining economic thresholds helps farmers know when to spray and when not to waste the time, money, and chemicals. It is an important concept in sustainable agriculture.)
Another reason to spray with only the sighting of a few beetles (with beetles there’s no guarantee you are going to be able to find them all, and they eat a lot quickly!), is that while these guys are currently enjoying our nightshade family veggies (tomatoes, eggplant, peppers), we just planted a whole bunch of different kinds of cucurbits (vine crops – cucumbers, squash, pumpkins, melons, etc.). As the name “cucumber beetle” might suggest, their preferred snack is cucumbers and other vine crops.
Cucumber beetles can make a good dent in the tomatoes and eggplant, but they will eat the entire plant right down to the ground on a newly germinating cucumber or melon. If we can control them now before the cucumbers start to come up, we should be in good shape.
Another reason to spray for cucumber beetles on young vine crops (in case you needed another) is that these early season cucumber beetles have overwintered from last year, and because of that it is possible that they are carrying a disease called Bacterial Wilt that they can transmit to the new crop. Bacterial wilt is NOT a fun disease to have in your melons (and cucumbers, to a lesser extent). As soon as a cucumber beetle vector (one carrying the disease) takes a bite out of your melon plant it transmits the disease. You won’t know it until mid-summer when your vines have nice, unripened fruit on them, and they suddenly collapse in a wilted heap. And there is nothing you can do about it. The only thing you could have done about it was to spray those cucumber beetles in the early season to prevent them from spreading the disease.
Cucumber beetles are one of the prettier vegetable garden insect pests, and I really kind of like them, in a twisted way. However, to my way of thinking, this is one pest that you want to hit with some type of pesticide early, rather than waiting. If you kill off the first generation (the one that may be carrying disease) then you should have a much lower population for the rest of the summer and a much lower risk of bacterial wilt. The worst case scenario would be waiting to control these insects until you have a large population in early to mid-summer that has been passing Bacterial Wilt to the plants, back to the next generation of beetles, infecting more plants, etc.
So what are your spraying options?
Organic Options: Rotenone (organic, but definitely NOT non-toxic), rotenone/pyrethrin combos, pyrethrin, pyrethrin/neem oil combos, neem oil. (This list is from most toxic and most effective to least toxic and least effective.) On a very low population, the neem oil can work okay, but it is a contact spray, which makes it less effective.
Synthetic Options: Permethrin (or pretty much any product that ends in -thrin and is labeled for use on vegetables). This is the synthetic form of pyrethrin/pyrethrum.
Obviously you would choose your spray based on your personal preferences, your willingness to spray multiple times, and your tolerance for insect feeding and other damage. This is a situation where, still several weeks away from any harvest, I would probably use a stronger product in hopes that I only needed to use it once.
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