Aphids on the Arugula?

One of my friends brought some arugula leaves to the office last week, to show me the many hundreds of aphids that were on them. The arugula is growing at a community garden that she had visited, and she had permission from the gardener to pick a few leaves.

Aphids on arugula from local community garden. PHOTO/Amygwh

We slid the leaves under the microscope and could see that, while a whole lot of the aphids are alive and active (the green ones in the picture), some had been "parasitized" by a wasp.

That means that a little wasp had laid an egg inside the aphid, and the egg was developing into a new wasp.

The aphids that have a baby wasp inside are the puffed-up golden ones in the picture.

When each wasp-baby is mature, it will bust out of the aphid body, leaving behind an empty aphid shell.

Are images from "The Alien" movie flashing through your mind yet? Sometimes, real life is just as weird as science-fiction movies. This is part of what keeps gardening so engaging.

In organic gardening, knowing that there are predators and parasitic wasps around, waiting to take care of a pest problem, provides an odd kind of comfort. Unfortunately, though, even if a swarm of ladybugs (surprisingly effective predators on aphids) moves in to help the wasps clear up the aphid problem, this arugula is going to need a lot of washing before it is added to a salad.

My venerable copy of Rodale's "The Organic Handbook of Natural Insect and Disease Control" (my copy is from 1996) offers some help for aphid infestations. The first suggestion is to wait for the predators to take care of the problem. Usually, in my garden, "waiting" is enough.

This is an odd year weatherwise, though, so it looks as though more active steps will be needed in some gardens. The next suggestion is to blast the little plants with strong spray from a hose to knock the aphids off. The next after that is to try an insecticidal soap spray. In a dire emergency, try a veg-garden-pest spray that contains neem.

Of course, the very first thing to have done, if anyone could have foreseen the aphid disaster looming from back in the fall, would have been to cover the little crop with a spun rowcover to keep the aphids out completely.

Hoping that other gardens are relatively aphid-free!

Field of Greens

At the little farm where Joe and I volunteer on Saturday mornings, the lower field has so many rows of greens - mustards, collards, radishes, and a little bit of kale - that there is no way for us to fully harvest the crop.

The guys who manage the farm, who pay attention to the farming lore of local old-timers,  plant the field each fall from end-to-end knowing full well that many perfectly good greens will go uneaten, just like in years past. For them, even though they enjoy eating greens, the main point of that crop is not so much Food as it is Pest Control.

They call those greens their "fumigant crop", and it is planted to keep the root-knot nematodes at bay. In spring, when they are ready to plant the warm-weather crops, they just turn under all the remaining greens to let them finish their good work of pest-control. Not too surprisingly, research supports the practice of the old-timers.

The book Managing Cover Crops Profitably, published by SARE (3rd edition, 2010), which can be downloaded for FREE, cites research that demonstrates the "nematicidal effects" of Brassica-family plants like mustard greens and radishes.

When I was talking with a county resident last week about his garden, he mentioned that he'd been having trouble with root-knot nematodes in his 1.5 acre garden over the past couple of years. I told him about my friends and their field of greens, and he went silent for a minute. Then he said that he hadn't planted greens as a winter crop for the past few years because his freezer was full, but he had in each of the previous 20 or so years of gardening in that spot.

I am pretty sure that, regardless of the state of his freezer, next September my new gardening friend will be planting a whole lot of greens.

Squash Beetles and Bean Harvests

Squash beetles look a lot like pale ladybugs.

It looks like a "good year" for squash beetles, because I have smashed a lot of them already. They are on both the zucchini and cucumber plants.

My camera hasn't wanted to focus on the little beetles, so the picture at the right is a bit fuzzy, but if you imagine a "washed out" looking ladybug, with seven spots on each side of its body, and it is eating a plant in the the squash/cucumber family, then you pretty much have a good picture in your mind.

Benefits of Crop Rotation

I have understood for a pretty long time that crop rotation, which involves the practice of NOT planting the same crop (or crops in one plant family) in the same location year after year, is important for a variety of reasons.

One reason is that plants in one family often are attacked by the same pests and diseases. Rotating out of a particular space, and planting crops from a different family there instead, can help reduce the buildup of diseases and pests that attack crops in one plant family.

Another reason is that plants in one family often make similar nutrient demands on the soil. Jessica Strickland of North Carolina Cooperative Extension, in a May 2013 article, wrote:

"Vegetables in the same family are similar in the amount of nutrients they extract from the soil, so over time planting the same vegetables in the same spot can reduce certain nutrients in the soil. If the same family of vegetables is planted every year in the same location, insect and disease problems continue to increase and soil fertility drops. Using pesticides and fertilizer could provide little help but over time they would not be able to keep up with the increasing problems."

Also, rotating to some particular crops can help reduce a pest problem that already has built up to damaging levels. An example pest is root knot nematodes, which can lower productivity of a crop pretty dramatically - if they don't actually kill the plants outright. A population of these soil-dwelling pests can be lowered by planting a bed solidly in one of the nematode-repelling marigolds or in a grass-family crop like rye, wheat, or oats.

What I didn't know until recently is the effect of crop rotation on the diversity of soil microbial life, the maintenance of which is so integral to successful organic gardens. In the Science Daily article "Why crop rotation works: Change in crop species causes shift in soil microbes", Professor Philip Poole of the John Innes Centre in England is quoted as saying,

"Changing the crop species massively changes the content of microbes in the soil, which in turn helps the plant to acquire nutrients, regulate growth and protect itself against pests and diseases, boosting yield."

Professor Poole added: "While continued planting of one species in monoculture pulls the soil in one direction, rotating to a different one benefits soil health."

Yet another good reason to plan a careful rotation in the veggie patch.

Gardens and Talks

This week I spent a couple of hours at a community garden in Smyrna, and it was mostly doing very well. It was great to see so many little gardens, and to meet more people who are focused on growing good food!

However, the garden was definitely having a pest problem. I have never seen so many beetles-per-square-inch before; these are kudzu bugs, and they were all over the pole beans:

So far, there is no good, established control method for these beetles, since they are new to the United States. Scuttlebutt has it that some entomologists at UGA are looking into the effectiveness of a parasitic wasp, but that's really all I've heard so far. It is likely, though, that if next year gardeners grow their beans under row covers, they will be able to avoid (or at least delay) such dramatic infestation.

The garden's tomato plants also had a problem, and I'm pretty sure it is Septoria leaf spot. The good news is that most of the garden beds already have produced a lot of tomatoes for the gardeners, so they have enjoyed a good harvest up to now.

The garden/farm where I volunteer on Saturdays has the same disease problem, and I'm guessing that it's only a matter of time before the leaf spot hits my garden, too. Disease has been a huge problem for gardens all over the area this year. Gardeners who are not all that concerned about using organic methods have been keeping the manufacturer of Daconyl (a fungicide) in business this year, and the rest of us are muddling through as best we can.

I pulled out the last of my Cherokee Purple plants yesterday, but I have several other tomato plants still producing, so I'm not totally heartbroken. Joe says that the Tomato Man's Amish tomatoes taste better, which means we still have what Joe thinks of as a "highly desirable" variety providing tomatoes for us.

Later today I'll get to visit another community garden, this one out in the north-east corner of the county, and I will be talking some about getting ready for planting fall veggies and about pest and disease problems.

On the evening of July 31, I'm scheduled to talk at the county Extension office about getting ready for the fall veggie garden. Anyone who wants to come should call the office to sign up (770-528-4070; or email uge1067@uga.edu).

Bad News Bugs

Just before I left town for another trip to Oklahoma, I saw three adults of the squash vine borer flitting among my plants, and I smashed two Mexican bean beetles in the bush beans. It looks as though the pests are going to be as early as the veggies have been! These are two pests that typically cause a lot of damage in my garden, and I know that my zucchini-days, especially, are numbered.

Also before I left town, I pulled up two tomato plants that were not thriving. The two were both Rutgers, which is normally my emergency backup, never-fail variety. Apparently, this gardening year is going to throw one curve after another at the veggie gardeners! When I pulled up the two plants, there didn't seem to be anything overtly wrong. The vascular system looked clean (not gunked up with fungus) and the roots were un-knotted (no root knot nematodes); the roots were not vigorous, though, and the plants weren't growing well. Since I don't know yet what went wrong, I planted sunflowers in the spaces those plants were pulled from.

I got back home on Tuesday evening and didn't have chance to do much more than take a quick look around the garden. Everything looked basically fine. But when I went around on Wednesday to check things out more closely, I saw that one tomato plant had been attacked by a pest:



The gaping holes and some black frass (poop) that had fallen onto some lower leaves were a huge give-away that the pest is one or more caterpillars, but I didn't see any at first. When I leaned across to the next plant, though, I found one:


This guy is very bad news. He/she is an armyworm, and like the squash vine borer and the Mexican bean beetles, this pest has made an early appearance. My copy of the book The Organic Gardener's Handbook of Natural Insect and Disease Control contains this somewhat alarming sentence about these caterpillars:

Larvae can consume whole plants in 1 night.

Needless to say, I have a date with a little sprayer full of Bt (the bottle I have is called Thuricide), the organic-approved pest control substance for caterpillars.

Even worse, when I was looking at the tomato-neighbor to the damaged plant, the plant on which I found the armyworm, I found some of these brown lesions on the lower leaves:


It's a little faint in the photo, but the ringed brown spot indicates a disease called Early Blight, which means that this particular plant is a goner. Several leaves had similar lesions. After verifying the disease with my handbook (hoping that my first guess was wrong), I got out a pair of pruners and a big garbage bag so I could get this plant out of the garden.

The plant was big, and it already had nice big tomatoes on it - making the loss especially annoying - and it had to be cut up to be removed from the cage. Cutting through the stems was a revelation! The insides of all the stems were already completely brown, and the lower stem was mushy inside.

I haven't decided yet what to plant in the space from which the diseased plant was removed. It shouldn't be another tomato or tomato-family relative, but that leaves a lot of options open.

Happily, the biggest problem some of my plants have is that they are so overloaded with pretty flowers that they are falling over.  Bee balm always reminds me of fireworks, but my husband thinks they look like Sideshow Bob, from The Simpsons.

Old Time Insect Control

My father told me a story this week about the Victory Garden his family had tended during WWII. The garden was in the vacant lot - with permission from the landowner - across the street from their home. They grew potatoes, pole beans, and "some other stuff." His recollection is that most of the garden was taken up by the potatoes, but there was a problem in the form of potato beetles, which were both abundant and voracious.

My father and his older brother, who were a little younger than 10 years of age at the time, had a job each day. They went across the street with two small blocks of wood each, and they used those blocks of wood to smash potato beetles. Each boy was required to clear a whole row of potatoes each day.

Apparently, I need to add some small blocks of wood to my tool bucket, for use at the garden/farm where my little family has spent some time smashing potato beetles. We have been flipping the beetles off the leaves onto a nearby hard surface, then smashing them with rocks, but bringing the hard surface to the beetles, in the form of a block of wood, makes a lot of sense.

New Pest: Kudzu Bug

A new, tiny brown bug - the Kudzu Bug - showed up in my yard last week, but other yards in the Atlanta area have been host to this insect for a couple of years now. A large number of calls to the local county extension office over the past year have been about this particular pest.

It shares that unfortunate habit of ladybugs of overwintering inside the walls of buildings, leading to occasional outbreaks of "what the heck?" when great masses of them emerge inside the building instead of outside, where they belong.

The really bad news is that this is not a "good bug" like the ladybug, devouring aphids and other small garden pests. The kudzu bug is itself a pest, not only on kudzu, but on all plants in the bean & pea family. It eats their leaves.

UGA's Dr. John Ruberson has published a short Pest Report (click the link to read it) about this new pest in the newsletter of Georgia Organics.

For farmers, the bug is a big problem partly because effective controls haven't yet been established, even though the bug is causing some serious damage. I am hoping that, for gardeners, the insect (which is a true bug - a Hemipteran) is not as much of a pest as the Mexican Bean Beetle, but I may have to resign myself to battling yet another beetle that eats my bean plants.

So far, my bean-beetle battle strategy includes early planting of bush beans, which works because the Mexican Bean Beetles become much more abundant as summer progresses. Sometimes, I don't see them until July, and by then I can already have harvested quite a lot of beans from bush-type plants.

According to the short article by Dr. Ruberson, the Kudzu Bug is showing up much earlier in the gardening year, and the bug in my garden suggests that he is right. That means my strategy of planting early bush beans isn't going to help much in the effort to avoid damage caused by Kudzu Bugs.

My other main strategy is to knock adult beetles into soapy water to drown them. Smashing the adults has also worked for Mexican Bean Beetles, even though it is pretty messy, but I have heard that the Kudzu Bugs have stinky guts, which makes smashing a less attractive strategy.

I also smash Mexican Bean Beetle larvae and eggs, and this would probably also work for Kudzu Bugs, but the smashing strategy isn't nearly as effective as avoidance by earlier planting of early-maturing bush beans has been. Smashing and drowning the pests just delays by a week or two the time when the crop is a complete loss.

It looks as though this will be a very interesting gardening year. Wish me luck!

EDIT: I usually get my basic information right, but in this post I originally had called the kudzu bug a beetle, and it isn't. The kudzu bug is in the order Hemiptera; it's a true bug. The information should be all correct now!

19 April 2013 EDIT: Anyone who is interested enough in Kudzu Bugs to have read this far should probably read the Kudzu Bug Update from 8 April 2013.

Mexican Bean Beetles

Every year brings its own trials. This year, the Mexican bean beetles have been ferocious. At the Plant-a-Row-for-the-Hungry garden, we tried spraying with Neem, but that didn't seem to bother the beetles at all. At home, I've just been smashing them, one beetle (or larva) at a time, but the beetles are winning. This is what most of the leaves on my pole beans look like:



And this is the adult form of the critter that is turning the bean leaves into lace:



The adult beetle looks enough like a ladybug (it is even in the ladybug family!) that most people would think it's a good guy. They would be wrong.

When the beetles are mature, they lay eggs, clusters of yellow dots. At some point, these eggs will hatch.



When the eggs hatch, what comes out doesn't look at all like a beetle. It is a fuzzy yellow larva. The larval stage of this beetle is heck on the leaves of bean plants. When I was looking for larvae to photograph, I couldn't find any young ones. These (below) have gone, I think, into the pupa stage.



When the pupa completes its development, it breaks out of its husk (like cicadas do) in the more familiar beetle form. There is an empty husk on the upper leaf in the picture below.



The big question is what to do about all these beetles. I am thinking about pulling up all the pole bean plants, but I still have cowpeas growing in another part of the garden. I am concerned that, without the pole beans around, those cowpeas will look a lot more tasty; right now, the cowpeas are bean-beetle free.

I have read that adult beetles overwinter in leaf litter, so I am definitely going to be turning the garden's soil some this winter, to make sure that remaining adults are exposed to whatever cold we have this year--- but last year we had a very cold winter; I am not sure how so many beetles survived!

Pest Control: Cucumber Pickleworms

Planting time is a good time to think about pest control, so I looked up the UGA fact-sheet on growing cucumbers and found a warning about cucumber beetles—keep them under control (through unspecified means) because they spread disease. That could be a useful warning, but I am pretty sure I have never had a problem with cucumber beetles. My pest problem in cucumbers is cucumber pickleworms .

Last year, the cucumber pickleworms had a very good year, and my cucumbers had a correspondingly bad year. Almost all of my cucumbers had the little shot-holes that show where a larva has eaten its way into the fruit. The little pests were also worse than usual at the Plant a Row for the Hungry garden where I volunteer, so I know the problem was not just in my yard.

I have a copy of The Organic Gardener’s Handbook of Natural Insect and Disease Control , and when I realized the cucumber harvest was in serious jeopardy I checked the pickleworm section for advice. One suggestion was to plant a “trap crop” of yellow squash, since the pickleworm likes those even better than it likes cucumbers. The other advice was to plant early maturing varieties of cucumbers so that a good harvest could be brought in before the pickleworms totally demolished the crop.

This advice might have been useful a couple of months earlier (at planting time!), but it didn’t help much at the time. However, spring has come around again, and I have another chance. I am not changing my cucumber varieties, though, because they already are varieties that mature fairly early, and I don’t really have the space for trap-crops, other than the zucchini that usually keels over before the onslaught of the pickleworm, so I am hoping for a different solution.

The Pickleworm Management page from North Carolina State University, recommends the use of Sevin (carbaryl) to manage pickleworms. People who are averse to using pesticides (even this one which is a relatively safe chemical for home gardeners to use), are going to hope for another option.

According to the fact sheet Cucumber, Squash, Melon & Other Cucurbit Insect Pests from Clemson University, pickleworms don’t survive winter freezing, and the adults fly up from Florida each year:

“In South Carolina, pickleworms starve or freeze to death during the winter. They overwinter in Florida and spread northward each spring. Severe damage usually does not occur before summer in South Carolina. Heavy populations generally do not build up before the first flower buds open; however, late crops may be destroyed before blossoming.”

It seems reasonable that when the Southeast has an early or unusually warm spring, or early, strong winds heading north out of Florida, the pickleworm damage might start earlier than usual, like it did last year.

A couple of those linked resources also mention that the parent of the pickleworm is a night-flying moth. This seems like information that could be used to thwart those pickleworms. I am thinking about covering some of my plants at night, to keep the moths from laying eggs on my plants, then uncovering the plants in the morning, so bees and other pollinators can get to the flowers.

This sounds like work, I know, and some of my cucumbers will be trellised and a serious hassle to cover up each night. So, I will leave the trellised vines uncovered and only cover the pickling cucumbers that will be sprawling on the ground this year. This way I will have both an experimental plot--covered-- and a control plot--uncovered-- (ignoring that they are different kinds of cucumbers), so the experiment may be able to tell me whether the nighttime covering makes a difference in pickleworm infestation.

I’ll let you know how the experiment turns out.