Garden Pests and Other Problems in Paradise

The Garden in September

I love it when visitors to my garden make comments like, "You've created paradise here." It makes all the hard work worthwhile when I hear their kind remarks. I find, however, that non-gardening friends are often unaware of the challenges from pests and diseases. I decided to document some of the problems that beset my garden this year, and note how I dealt with them.

RABBITS AND DEER

Not just this year, but every year we have our share of rabbits and deer. Currently, a family of rabbits are living under the potting shed in the kitchen garden. They must have heard that real estate is all about location, location, location ...

Pesky rabbits abound in my garden.

Deer pass through the garden regularly. My favorite picture, which I took it a few years back, is the thumbnail at the end of this posting. To prevent the rabbits and deer from treating my flowers and vegetables as their own personal smorgasbord, I begin a spraying regime early in the spring. I use a commercial deer and rabbit repellent and I change brands as the summer progresses, so they don't get too accustomed to one type. This works very well for me, although the only sure deer repellent is a high fence. In addition to the spray, as much as possible, I choose deer-resistant plants. Of course, no plant is completely deer resistant -- they will eat anything if they are hungry enough, although I have never seen a nibbled daffodil!

APHIDS
This year I see aphids, but not monarch butterflies, on the milkweed. Aphids are soft, pear-shaped, and very tiny. They reproduce like there's no tomorrow and both adults and nymphs suck plant sap. Aphids are easy to remove by spraying them with water from the hose, or with horticultural soap. I use organic gardening practices, so nothing stronger than this.

Yellow aphids on milkweed.

The ladybug is the aphid's natural predator. Unfortunately I have too many of these particular pests and not enough predators to control them.

A determined ladybug chewing on aphids.

Talking about milkweed, this morning I had a wonderful surprise. If you follow my blog you know I haven't seen monarchs on my milkweed this year. Read my posting "... and Where Are All the Monarchs?" (click on the title). At least one must have visited, however, because I found two monarch caterpillars! Hurray! Not my usual bounty, but I am excited.

NOT A PEST -- the monarch caterpillar.

JAPANESE BEETLES

For a couple of years we had few Japanese beetles here, but this year they skeletonized the leaves and demolish the blooms of my roses. On my morning tour of the garden, I pick off these shiny beetles and drown them in a container of soapy water. I don't bother to invest in those beetle bag traps, as they tend to attract more beetles to the garden than otherwise would have been there. As an organic gardener, hand picking is my preferred method of control.

Japanese Beetle Popillia japonica.

The Japanese beetle larvae are white grubs that feed on organic matter and roots of grasses in the soil; they can cause a great deal of damage to your lawn. In my area, we control them with bacterial milky spore. You should apply milky spore to the lawn every year for three years as the spore count must build up to be very effective. Another control -- insect parasitic nematodes have recently become commercially available. Apply the nematodes when the white grubs are small, irrigating before and after applying them.

RED THREAD

When I saw bare patches on the shade-garden lawn this spring, I thought they were caused by the grubs of the Japanese beetle. I found that the infected patch could not be lifted out when I grasped and pulled it, so the crowns and roots were not infected by grubs.  On closer examination, I saw the antler-like structures (sclerotia) produced by a fungus on the tips of the infected leaf blades. The threads are a pink/red color hence the name, red thread.

The patches on the lawn are caused by red thread.

I believe the fungus occurred following higher than normal rainfalls in late spring -- the shade-garden lawn does not drain well and it was like a wet sponge for days. The red thread fungus can be treated with a fungicide, but as the disease does not kill the lawn, I decided doing nothing was the best option for me. 

CUCUMBER BEETLES

These little buggers attacked my zucchini this year (not the cucumber plants). I planted a yellow squash and two zucchinis, but only one zucchini survived, and that was attacked by beetles. As larvae of the cucumber beetle feed on the roots of squash family plants, killing or stunting them, I think this is what happened to the two plants that were lost. 

Striped Cucumber Beetles

Cucumber beetles lay their eggs at the roots of plants, so I have removed and destroyed crop residues where adults overwinter. Next spring I will plant squash in a different place and cover the seedlings with floating row covers. I will hand-pollinate the covered squash family plants. The good news this year -- I still harvested plenty of good zucchinis from my one remaining plant although the beetles attacked it.

SQUASH BUGS

Another problem is the squash bug which looks something like the stink bug.  I find they are easier to control than cucumber beetles as they lay their eggs on the leaves. Squash bug eggs are shiny, slightly oval, and copper colored. Every morning I inspect the plants and scrape off any new eggs. If any hatch, I spray with insecticidal soap which kills them on contact.

TREE BORERS

The first indication that the roundheaded appletree borer was attacking our old pear tree was the activity of the pileated woodpecker. He visited regularly, pecking a large hole in the trunk. We noticed some rusty-brown, grainy-looking stuff on the ground under the hole. This is the frass the lavae eject from their tunnels.

Pileated Woodpecker searching for grubs.

H.H. probed a flexible wire into the tunnel to remove the large white grubs. The borer may destroy the tree; we are not hopeful it will survive. We could apply chemicals, but prefer not to do this. This very old tree is living on borrowed time as pear trees usually only live for less than 20 years. H.H. has known it all his life and it will be a sad day when it goes.

RUST
Rust and hollyhocks go together. The hollyhock (Althea rosea syn) rust (Puccinia malvacearum) is a fungus that requires only one host to complete its life cycle.

Hollyhock Alcea with spots of rust on its leaves.

The fungus initially appears as light yellow-orange spots on the upper surface of leaves. These develop into brown pustules on the underside of leaves. Pustules may also develop on the upper side of the leaves (a different spore stage) and on stems and green flower parts. My hollyhocks suffered a severe infestation this year with the leaves dry and hanging down along the stem.

Control is difficult: plant them in a location that has plenty of air circulation with plenty of space between plants to reduce the chance of infection. Increased humidity around the plant results in increased production of rust spores, so I avoid wetting the foliage when watering.  According to Colorado U. Extention, "Sanitation is critical ... as the fungus overwinters in pustules in basal leaves and in old stems. The removal of all infected plant parts in the fall and removal of dead plant parts in very early spring is very important. Rusted leaves should be removed as soon as they appear during the growing season and flower stalks should be removed when flowering is over. Plant debris can be burned, buried in the garden or buried in the compost pile"

I applying a layer of mulch around my hollyhock in the spring to help prevent spores overwintering on plant debris at their base from infecting new plant tissue. It is important to remove mallow weeds (cheese weeds) from the area, especially Malva rotundifolia, as they carry the spore. I apply a preventative treatment of fungicide prior to infection. Periodic applications of wettable sulfur, begun several weeks before rust normally appears is recommended. I find it is a losing battle, but as hollyhocks are an important element of the cottage garden, I continue to fight!

ASTER YELLOWS
I wrote about aster yellows last year in my September bloom day posting. You can read it here. I removed the infected Echinacea because they developed secondary flower heads, like little green leaves, which emerged in a cluster from the primary flower head. A few of the plants developed the disease again this year, so H.H. dug them out. Aster yellows is caused by a tiny organism called a phytoplasma, similar to a bacterium. The organism is spread by insects. There is no treatment other than removing the infected plant.

Purple Cone Flower Echinacea purpurea with Aster Yellows

No powdery mildew this year, not even on my phlox, which is amazing as it is prevalent in wet weather, and we had the wettest August I can remember. I wrote an article about it for eHow, "My Phlox Has White Spots on Its Leaves" -- click on the title if you would like more information.

These were not my only garden problems, but this is a long posting. Congratulations if you read to the end! What problems did you encounter in your garden paradise this year?

Your gardening friend,
Pamela x

My mini horse with his dear/deer friends.

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