It’s August and everybody’s vegetable gardens crank out delicious organic food. Yum-oh! But sometimes gardeners find holes in the middle of the leaves of their vegetable crops. Large holes. Many of them. Who’s the culprit? Caterpillars? Grasshoppers? Beetles?  Or maybe snails!

Snails and slugs both glide through your garden on a ribbon of slime, the shiny, sparkly stuff the snail in the photo above is leaving behind. At bottom left you can see the slime glistening on the ground. These animals are mollusks, related to oysters, clams, and octopus.

A trail of dried slime across the large hole in this green pepper is the definitive clue. A snail or slug definitely made this hole. Anytime you find holes in the leaves or fruit of your vegetable plants look for slime. Slime, this incontrovertible evidence tells you who to blame. And then you know how to fix it.

If you catch the buggers red-handed in the act of destroying your produce you don’t even have to search for evidence. This slug has just devoured the side of a friend’s tomato. Yuk!

But often, you can’t catch them in the act because they hide in the heat of the day. They come out at night, on overcast days, during rain storms, or when the sprinklers come on. They like it cool and wet and they hide under boards and pots – in any cool, shady, damp place where they can survive the mid-day sun and heat.

You can go out into the garden at night with a flashlight and hand pick snails easily. Just pick them up by the shell put them in a brown paper bag. Then you can step on it to crush the critters and bury it in your compost. Slugs, however, have no shells and are too slimy to pick up. Because slugs and snails hide during the day you can also make traps for them and that way you don’t have to go out at night with a flashlight. Put upside-down flower pots around your garden. They’ll hide inside them where you can easily harvest and destroy them in daytime comfort.

Iron phosphate controls these mollusks in the garden. You’ll find it under the brand name Sluggo. Iron phosphate is not toxic to pets, children, or birds. It also has no effect on insects. It kills mollusks and only mollusks. Slugs and snails eat it and they die.

 Older style, toxic, non-organic slug bait uses a poison called metaldehyde. Metaldehyde is poisonous to your pets, your kids, and wildlife. Avoid it.

 Some people swear by beer to kill slugs and snails. You’re supposed to put a shallow bowl of beer out in the garden, the slugs and snails are attracted by the odor, crawl into the beer and drown. Maybe I just don’t do it right but it’s never worked for me. 

 The damage they do kills your plants!

An infestation of these bugs causes the leaves of your squash plant to turn yellow. The whole plant slowly turns brown and dies.

If you think you have squash bugs, look on the underside of the leaves for clusters of tiny, brown, football shaped eggs. These eggs can be anywhere on the plant (leaves, leaf stalks, stems) but they won’t be on the upper surface of the leaf where you can spot them easily. You have to turn the leaves over and look on the underside. Look all along the stalks and stems as well. When you find eggs, destroy them. Remove the leaf tissue with the eggs on it and crush the eggs. Or just smash them in place with your thumb.

When the eggs hatch, the baby squash bugs look a bit like aphids except that they move around fairly quickly and aphids don’t. Babies of true bugs are called nymphs. They look somewhat like the adult squash bugs except that they don’t have wings. Squash bugs, like grasshoppers, aphids, and stink bugs have incomplete metamorphosis from egg to nymph to adult. The baby insects in this group look like miniature adults in most cases. (On the other hand, insects that experience complete metamorphosis, like butterflies, bees, and flies grow from egg to larva to pupa to adult. A baby butterfly, a caterpillar, looks nothing at all like the winged adult.)

As squash bug nymphs grow they get bigger and easier to spot. They crawl all over your plant. Like all insects, the nymph has to molt (break out of its hard exterior shell, its skeleton) as it grows. You may find some left-behind shells stuck to your plants. Eventually, the nymphs reach their maximum size. Then they are ready to become adults.

The winged adult squash bug flies swiftly. Moving fast, they can be difficult to catch. Sometimes you can catch them in the morning before the day gets hot. Insects become more active in heat, less active in cold. Carry a jar of soapy water with you and dump all the bad bugs you catch into the soapy water. They die quickly (which is very satisfying!). Because the adults are good fliers they fly into your garden from your neighbor’s garden.

Starting your squash plant seedlings under row covers of light weight fabric that lets in sunlight, air, and water but keeps bugs out will protect them from the adult squash bugs and give them a good start in life. Eventually though you have to lift the covers to allow the bees to pollinate the flowers or you’ll have no fruit. You can hand pollinate the flowers yourself and keep the plants under cover if you wish. Even so, many squash plants get huge and are hard to contain under cover.  

 Go out into your garden every day, search for squash bug eggs, and crush them. Since the nymphs don’t have wings they can’t get away from you very fast so knock them into your soapy water or smash them with your hands. You can also squirt them with insecticidal soap but be careful because squash plants are sensitive to soap and you can damage your plants. If you make your own soap spray, be sure to use a genuine soap, not a detergent.

We recently visited two side-by-side gardens in Albuquerque, New Mexico. One garden, where the green peppers and other vegetables are thriving, is all organic. Every morning the organic gardener goes out to inspect her squash plants, and she finds and crushes all the squash bug eggs. There are no squash bugs on her plants and her plants are healthy.

The neighbor is not organic and uses any harsh chemical he can find. Most of these photos of problems came from the non-organic garden. Because the ecology of the non-organic garden has been completely disrupted by the indiscriminate use of broad-spectrum insecticides, the predators have been killed. As a result, the non-organic garden has many more problems than the organic garden.

 All of the true bugs have piercing-sucking mouthparts like hypodermic needles. The bugs that damage our vegetable gardens are ones like stink bugs, squash bugs, harlequin bugs, and tarnished plant bugs. But there are also good bugs, beneficial predators, like minute pirate bugs, that use their needle-like mouth to stab other insects and suck the life out of them. Aside from the bugs you find in your garden there are also bugs like bed bugs and kissing bugs, ones that feed on us humans by sucking our blood.

This green stink bug has its needle-like mouth parts inserted into a flower bud and is busy sucking nutrients out of the plant. You can clearly see that the hard forewings (green with yellow dots) only cover half the bug’s back. The membranous hindwings stick out from underneath the forewings and are easily visible to the naked eye. Stink bug feeding leaves Yellow spots of damaged tissue on developing fruits are the tell-tale clue that stink bugs leave behind.

This insect is a spotted asparagus beetle, not a bug and not a lady beetle. Like all beetles, the hard, colorful forewings (red with black spots in this example) completely cover the abdomen and the membranous hindwings are not visible. Beetles have chewing mouthparts, unlike bugs. This pest lays eggs on asparagus plants, and its larvae eats the asparagus berries.

All of the true bugs have incomplete metamorphosis where their babies (nymphs) look like the adults but without wings. The bug nymph shown here on an asparagus plant has very rudimentary wings and strongly resembles the adult bug. When it reaches maturity it will have well developed wings like the green stink bug in the first photo shown above.

The squash bug feeds on squash plants and their relatives. It, like the stink bug, is a true bug. The adults and the babies (nymphs) stick their sharp little beaks into the leaves and suck out the nutritious sap. They can seriously damage your summer and winter squash, and pumpkins, but they will also feed to a lesser extent on any other member of the cucurbit family. The nymphs look a bit like gigantic gray aphids clustered on the undersides of the leaves. When they reach adulthood they have well developed wings and are swift flyers.

In contrast to insects that have incomplete metamorphosis, those that have complete metamorphosis, like butterflies, have babies (larvae) which do not look anything like the adult. The butterfly larva is a caterpillar, a very different creature from the adult. The fly larva is a maggot, also very different from the adult.

 Effective organic controls for pesky true bugs in the vegetable garden include hand-picking where you grab them and dump them into a jar of soapy water. Insecticidal soap is also safe and easy to use. Just be sure that the bug you spray is actually a pest and not a beneficial insect because the soap will kill pests and beneficials alike. If you are plagued by bugs in your vegetable garden this year, think about putting up some row covers next year to exclude the bugs completely.

 Be careful and think twice before using any chemicals to control insects in your vegetable garden. Remember, you’re growing food that you intend to eat. Never spray your food with poison. 

Very familiar to most gardeners, aphids (aka green flies in the U.K.) attack almost all vegetable crops. There are thousands of different species in different colors (green, black, gray, yellow or reddish-brown). Sedentary, they don’t move around much. They just sit still and suck. Some species transmit mosaic virus diseases.

Tiny thrips on an onion plant. They have rasping mouthparts. They file away the soft tissue from leaves and flowers causing silvery discoloration. Active flyers, thrips transmit tomato spotted wilt virus.

Mealybugs don’t even look like insects. They look more like q-tips in the leaf axils and undersides of leaves. They are sedentary. They transmit mealybug virus to pineapple plants.

Leafhoppers come in an astonishing array of colors, and some are quite pretty. Common garden variety leafhoppers are generally pale green, wedge-shaped, and jump away when disturbed. These are active flyers with sharp little beaks. They transmit aster yellows (a serious mollicute disease) and viruses like beet curly top and yellows virus.

 Along the way we might run into beetles. Some beetles, like ladybugs (aka lady beetles), are good partners. Beneficial insects such as these help you achieve your goals by eating insects that damage to your plants. Other beetles damage your plants:

Japanese beetles. They’re busy eating holes in these leaves (well, they’re busy doing other things as well) and can seriously damage a very wide range of garden plants. These beetles only occur east of the Mississippi. The ones shown are the adults. Their babies (whitish grubs with brown heads that curl into a “C” shape) live in the soil and eat plant roots. You can hand pick the adults and knock them off the plants into a can of soapy water. Beneficial nematodes that also live in the soil attack and kill a wide variety of soil dwelling insects, including the larvae of Japanese beetles.

Colorado potato beetles. The adult is on the left and a baby (larva) on the right. The adults and larvae have voracious appetites for numerous garden plants and can be quite destructive. The soapy water trick works on adults and larvae alike. Bt san diego (Bacillus thuringiensis var. san diego), a parasitic bacterium that infects and kills beetles and only beetles, provides excellent control. Be careful to get the variety san diego for beetles. The more common variety of Bt is var. kurstaki which only kills caterpillars and will have no effect at all on your beetles.

Flea beetles. So called because they are very tiny and hop like fleas. These insects are too small to hand pick. They chew lots of small roundish holes in leaves and can make eggplant leaves look like lace. Their larvae live in the soil and eat plant roots. Thus beneficial nematodes make a good remedy for these beetles.

Curculio or Weevil. The long snout is the give-away.  This is a rose curculio on a ‘Harrison’s Yellow’ rose flower. They eat holes in the flower petals, chew up the stamens and lay their eggs in the flower. Hand-picking into soapy water works on these guys. The larva is a legless, whitish grub with a brown head. It drops to the ground when it’s ready to pupate to become an adult. Because it spends part of its life cycle in the soil it is also vulnerable to beneficial nematodes.

Ladybug (aka lady beetle). Not really a bug at all but a true beetle. There are many species of lady beetles and all of them are valuable partners in the garden. They are voracious predators of aphids and other soft bodied insects so they really do a good job of protecting your plants.

Home gardeners love to grow members of the squash family, the Cucurbitaceae, called cucurbits for short. This big, important family includes all types of squash: winter (like acorn and butternut), and summer (like zucchini). It also includes cucumbers, pumpkins, melons in the genus Cucumis (cantaloupe, Persian, honeydew, casaba) and watermelon, in the genus Citrullus.

Keep in mind one very important fact about all these delicious vegetables and fruits:  they are all warm season crops. This means that they are sensitive to cold temperatures. And this sensitivity can cause stunting and lack of fruit.

Vegetable starts of warm season plants are readily available in nurseries and garden centers early in the season, when temperatures are really still too cold for them to thrive. As a result, when gardeners plant them too early, the plants simply sit, growing slowly or not at all, and become stunted. They usually begin to grow well when the weather warms up. So the answer to the first question is the squash doesn’t grow because it is still a bit too cold for it.

These two summer squash, each about 3 inches tall, wait for warmth. They’ve not grown significantly in the two months since they were planted. The photo also illustrates the second problem that crops up this time of year. Both plants above are flowering, but all the flowers are male. Male flowers do not make fruit. Only female flowers make fruit. All members of the squash family have female and male flowers on the same plant, but they produce only male flowers early in the season while temperatures are still cool. They start producing female flowers later in the season.

Here’s a female cucumber flower. See the spiny baby cucumber holding this flower up? That fat spiny structure below the petals (that is, closer to the plant) is the ovary of a female flower. The ovary is the thing that matures into a fruit, whether it’s an acorn squash or a zucchini. No female flowers, no fruit! And that’s the answer to the second question.

Look at the stalk holding up this male zucchini flower. It doesn’t look like a miniature zucchini at all. That’s because it isn’t. This stalk is merely a stalk. This flower does not have an ovary because it is a male flower and it will never mature into a fruit. The male flowers produce the pollen needed to fertilize the female flowers.

A female flower of a yellow summer squash clearly has a large yellow ovary underneath the flower petals. The ovary looks like a miniature squash. After the female flower gets pollinated it matures into a delicious squash.

 Next time you wonder why your cucurbit plants sit and sulk, or your zucchinis make flowers but no fruit, just be patient. Keep your vegetable starts where they are warm and have plenty of sun. Put them outside in the garden or a container when the weather warms up.

The theme of the show this year was “Passport to the World”, and exhibits highlighted the flowers of South Africa and other exotic locations. Of course, I was particularly enamored by the orchids, as usual. And the display by Waldor Orchids was exceptional. Their display represented the National Orchid Garden of Singapore and allowed us to imagine what it must be like to be there, in Singapore, seeing the orchids in the garden.

Here are some photographic highlights of the beautiful orchids we saw.

A splash-petal Cattleya hybrid with a peloric gene that makes the petals similar to the lip.

A bright red cattleya alliance hybrid that looks like a Sophrolaeliocattleya to me.

A spectacular Vanda, probably close to Vanda rothschildiana a hybrid between Vanda coerulea and Euanthe sanderana.

The lovely Ascocendas, hybrids between Vanda and Ascocentrum, are delightful and colorful miniature vandas.

Oncidiums, sometimes called "dancing ladies" in Hawaii, are always lovely.

David Deardorff

It’s time to get started on the vegetable garden for the coming season so you can grow your own healthy, organic food again this year. Many of us have already started seedlings indoors to transplant out to the garden or the cold frames as soon as weather permits. Kathryn and I have come up with a checklist of ten things to consider before you plant. Each item on the list helps to prevent pests and diseases in your vegetable garden. All ten of them acting in concert really gives you a leg up for a successful and productive year.

1. Sanitize. If you didn’t get around to cleaning up old left-over garden debris last autumn, do it now. Pay special attention to any dead plant material from diseased or infested plants and get it out of your garden. Fungal spores, insect eggs, and bacteria lurking on old infected dead leaves lying on the ground can quickly infect your new plants and ruin your produce all summer long.

2. Right plant, right place. Be sure and read the instructions on the seed pack or the vegetable start plant label and put your plants in the best location to meet those requirements. If your plants have the right amount of light and water, the correct temperature, and the proper soil they won’t be under stress. And stress, as we all know, predisposes our plants (as well as ourselves) to attack by pests and diseases.

3. Light and air flow. Most vegetable and fruit plants want full sun and free air movement. Plants that do not get enough sunlight will be weak and spindly, and won’t be able to produce very much food for you. Free air movement helps foliage dry quickly and helps to avoid diseases and pests so don’t crowd your plants, give them space.

4. Genetic resistance. If you have a choice, choose cultivars that are genetically resistant to diseases and pests. Less disease and fewer pests means less work for you and more produce. Sounds like a win-win to me! Most all of these disease resistant cultivars have been developed through traditional plant breeding techniques.

5. Manage water. Set up your garden so that your watering practices deliver water to the root system, not to the leaves. Keeping the leaves dry goes a long way to avoiding diseases. In general, keep your plants evenly moist for best results. Allowing your plants to get extremely dry and then flooding them to get them extremely wet results in uneven growth, deformed foliage, and reduced yields. Also try to group plants according to their watering needs.

6. Proper temperature. Some vegetables like tomatoes and sweet corn, and fruits like melons are warm season crops. These are plants that flourish in hot humid weather. Other plants like cabbage, lettuce, and spinach are cool season plants that flourish in cool temperatures. If you put warm season plants in the ground in early spring while soil and air temperatures are still quite cool, they will not grow well and may be stunted. Conversely, cool season plants planted in mid-summer may simply flower and set seed while still very tiny.

7. Build soil. Creating healthy, biologically active soil is the best way to build healthy plants. Incorporating dead plant material (not diseased!) into the soil feeds micro-organisms that break it down into simple nutrients that will ultimately feed your plants. Feeding the soil results in a complex ecosystem filled with fungi, bacteria, insects, worms, and other critters that help to out-compete the ones that want to damage your plants. Compost and organic fertilizers incorporated into the soil are excellent sources of dead plant material with which to feed your soil. Mulch placed on top of the soil around your plants will also eventually break down and feed the soil.

8. Polycultures. A polyculture is where you put lots of different plants into the same location. Corn, beans, and squash, for example, is a traditional polyculture developed by the Pueblo Indians of the Southwest centuries ago. The corn, beans, and squash are all planted together in the same bed. You can mix vegetables and fruits into your flower beds and vice versa. The important benefit you get is that it makes your plants harder for pestiferous insects to find. It also makes it difficult for fungal and bacterial disease to jump from plant to plant.

9. Rotation. Don’t put a plant in the same location where you grew it last year. Move your plants around from year to year to make them moving targets. It helps to avoid the build-up of soil-borne pests and diseases. There are lots of crop rotation systems and schemes, you can choose one of these or just create your own system, one that works for you. Many people find that a three-year rotation system works well.

This hornworm caterpillar was eaten alive by a parasite.

10. Beneficial organisms. There are lots and lots of insects and other critters that are willing and able to eat the insect pests that want to eat your produce before you do. Many are predators, like lady bugs and lacewings, and some are parasites that lay their eggs inside other insects. And then there are beneficial nematodes that attack and kill insects that live in the soil. Many birds are also insectivorous and can help to get rid of insect pests for you, and so can frogs, toads, and spiders. If you manage your garden to protect these beneficial critters, they will help you manage the pests.

David Deardorff

In my blog last week I wrote about visiting the Northwest Flower and Garden Show many years ago with my mom and dad and several siblings. We all spent a lot of time viewing the fabulous orchid displays. Last week Kathryn and I spent a wonderful time at the 2010 show. We presented a seminar on Sunday afternoon, we went to hear other experts speak, and we visited the fabulous displays. I found myself enchanted by the orchids once again at an elaborate display installed by the Northwest Orchid Society and featuring a large number of Paphiopedilum orchids, warts and all.

Paphiopedilums, known as slipper orchids, have fascinating flowers featuring warts, hair, and beautiful colors. The lowermost petal is shaped like a pouch, giving rise to the common name, slipper orchids.

Some boldly flare open with their petals spread wide.

Some are attractively curvaceous, rather seductive and feminine (to me anyway).

And some have an elaborately developed lip. This might actually be a Phragmipedium hybrid, the new world counterparts to the paphs.

Almost any Paphiopedilum is an excellent choice for a companion plant in your home. In general, they prefer the low light conditions and the warm nighttime temperatures found in most of our homes.

David Deardorff

We’ve been coming to the Northwest Flower and Garden show in Seattle for years and it’s always exciting to see what’s new, see the extravagant displays, and hear experts speaking on various subjects. We’re really looking forward to coming back to this lavish display of the latest and greatest in the gardening world. This year, the show starts on Wednesday, Feb. 3 and Kathryn and I are presenting a program on Sunday, Feb. 7.

I remember the first time I ever attended the show. It was many years ago. Kathryn and I went with my mother and father, and several of my siblings and their spouses. It was quite a family affair with all of us crammed into the orchid displays oohing and ahing over the amazing orchids. At the time, Kathryn and I owned an orchid nursery and tissue culture laboratory in Hawaii and my father had a greenhouse full of orchids in the backyard of his home.

BLC Larry's Gem, a hybrid in the Cattleya alliance.

This photo is of BLC Larry’s Gem, a hybrid created by Kathryn and me in our orchid nursery in Hawaii and named in honor of my father, Larry. We registered it with the Royal Horticultural Society in Great Britain, the official registrar of all orchid hybrids.  BLC Larry’s Gem is in the Cattleya alliance, with very large flowers on a large vigorous plant. Most members of this alliance are tricky to grow as houseplants because they want more light than some other kinds of orchids.

Phalaenopsis orchids come in white, pink, yellow, and can be spotted or striped as well.

Phalaenopsis hybrids are much easier to grow in the home than Cattleya alliance orchids. Called moth orchids, they prefer the low light levels and warm temperatures found in the average home.

Paphiopedilums, or slipper orchids, also have flowers in a wide range of colors.

Paphiopedilums, or slipper orchids, are also easy to grow as houseplants. Like moth orchids, they prefer the shaded warm conditions provided by the average home.

At the Northwest Flower and Garden show you will see numerous examples of these and many other kinds of orchids. Check it out. You’ll be glad you did.