Category Archives: IPM

Troubles in the Garden

Milkweed_aphids
Milkweed aphids

Some of us enjoy sitting in our gardens, relaxing and watching birds and other wildlife. Others grow fruit and vegetables and know their way around the kitchen. Whatever you like to do sometimes pests get in the way.

In my own garden recently I discovered my butterflyweed covered with yellow milkweed aphids. They’re not interested in any other plants just this one. Oleanders get this same sucking pest also. I’ve washed them off twice with a strong spray of water but must have missed a few as they are back. Unfortunately, I haven’t seen any monarch butterflies to help me with this problem. I’d rather not even use an organic pesticide to control the outbreak. It would harm any monarch eggs that I’ve overlooked.

With pest control on my mind this week, I received an email from fellow Press Banner columnist, Dr. Terry Hollenbeck. “I thought of you when I found an article in an old gardening magazine”, he wrote. “It’s ‘The Home Gardener’ and was published in September, 1945.”

DDT ad_The-Home_Garden-Sept1945
DDT ad in ‘The Home Garden’ magazine published September 1945

Dr. Hollenbeck scanned the pages from his own magazine and sent them to me. Terry goes on to note that the editorial about the new wonder insecticide DDT warns readers in 1945 to proceed cautiously with it. Then later in the magazine on page 99 in a half page ad there appears an advertisement for DDT, the “Army’s sensational insect killer that gardeners have been waiting for…that is absolutely safe to spray”.

There has been a lot of research now on DDT and it’s effects on our bodies and that of wildlife. I was surprised when I Googled DDT that it’s still being used in the world and also found a published study debunking it’s adverse effects on raptors. Guess one can find statistics to support any argument if you look hard enough.

Here is what I found out about current use of DDT that I found interesting.

Back in 1972 the EPA (Environmental Protection Agency) issued a cancellation order for DDT use in the United States based on research showing adverse environmental effects to wildlife and potential human health risks. Studies have continued to show a relationship between DDT exposure and reproductive effects in humans and as a result, today, DDT is classified as a probable human carcinogen by U.S. and International authorities.

India is the only country now producing DDT. China and North Korea having discontinued production in recent years. 12 countries still use DDT for vector control of mosquitos and protozoa – the parasitic diseases of malaria, dengue and black fever which kill more than 800,000 people each year.

Many organizations are now promoting an integrated approach to mosquito and protozoa carried diseases. It’s not a DDT or nothing solution. Some of these organisms are developing a resistance to DDT and other chemicals. Like in our own backyards, you have to look at the whole picture. Successful programs to educate communities about non-chemical methods of control mosquitos are underway in many countries such as Vietnam.

DDT is known to be very persistent in the environment. It accumulates in fatty tissues and can travel long distances in the upper atmosphere. Because of its persistence, there is still concern for residues in the U.S.
Today nearly 40 years after DDT was banned in the U.S. we continue to live with its long lasting effects. According to the organization Pesticide Action Network, USDA found DDT breakdown products in 60% of heavy cream samples, 42% of kale greens and 28% of carrots. These breakdown products of DDT were found in the blood of 99% of people tested by the CDC.

Something to think about when I see all those mustard yellow aphids on my asclepsias. Maybe I’ll get the hose out one more time or rub them off with a gloved hand.

Growing Wine Grapes

Napa_Valley_vineyard.2048Prune orchards once reigned supreme in the Napa Valley. Pears, walnuts and fodder for grazing sheep were also grown where now 45,000 acres of premium wine grapes flourish. The crush is on in Napa County.  Mostly cabernet sauvignon, chardonnay and merlot are being harvested at night but back in 1928 the prune crop was worth twice as much as wine grapes.

We all have an insect or two that we have to deal with in our gardens.  I found out on a recent excursion to Napa Valley that all those acres of grape vines could possibly be lost if the European grape moth has its way. Believed to have been imported in vegetables from Europe it was first detected in Napa County in 2009. Back in 2011 Santa Cruz County was dealing with the same pest. With quarantine efforts and eradication of fruits and flowers near the area where they were first detected our county hasn't had much of a problem with them since.

Integrated pest management is the ecologically sound approach to pest control. In Napa County, I learned that the European grape moth is being well controlled in recent years by organic sprays such as spinosad and BT. Another very effective control method used is mating disruption with pheromones.

These techniques might not be as picturesque as planting roses around a grape orchard as an early cabernet_sauvignon_grapes.2048warning system for fungal diseases but they have worked for the grape moth. Roses are traditionally planted at the perimeter of vineyards as both they and grape vines are prone to powdery mildew and Downy mildew in our Mediterranean type climate. If powdery mildew appears on the roses, the vineyard can be sprayed with sulfur. Although sulfur does not cure powdery mildew, it will prevent it.

Downy mildew is another deadly mildew that attacks the green parts of the grape vine. Once Downy mildew is detected on the rose bushes, the grape vines can be immediately sprayed with a solution of copper sulphate and lime.

Many of the vineyards also plant lavender and rosemary to repel many harmful insects, provide habitat for beneficial insects preying on undesirable insects and add a pleasant flavor to the wine.

cabernet_grapes_ready_for_crush.2048Sitting outside on a tasting room patio planted with beautiful flowering shrubs and perennials it's hard to imagine the delicious wine in your glass doesn't come effortlessly on the part of the winery. Like our area that grows pinot noir grapes exceptionally well, the terroir of the Napa valley is expressed in the flavor of its wine. The qualities of the soil, geography and climate all contribute.

A vast array of soils of volcanic and marine origin coexist in Napa Valley. Half of the world's soil orders occur here with more than 100 soil variations all affecting the character of the grapes. Soils guide the grape grower as to which rootstock and grape varieties to plant.  Valley floor soils tend to be deeper and more fertile and produce vigorous growth so the crop must be tightly managed to produce concentrated grapes. On the hillsides the vine has to struggle to survive the spare, rocky soils and naturally sets a smaller crop, producing smaller grapes of highly concentrated color and flavors.

Walking among the vines, I noted drip irrigation in use. I found out that traditionally Old World wine regions consider natural rainfall the only source of water that will still allow the vineyard to maintain its terroir characteristics. Spain has recently loosened the regulations of the European Union Wine Laws and France has been reviewing the issue.

Grapes depend on a certain amount of water mainly in the spring and summer and so here in California as well as other summer dry regions of the world like Australia, the vines are irrigated starting in May or June. It's a fine line to determine how much and how often to irrigate to preserve the flavor of the grape and not just grow lush plants with high yields.

In our own gardens we can train a plant to put down deep roots decreasing the amount of watering it needs. So it is in grape growing where the vine receives sufficient water during budding and flowering but irrigation is then scaled back during the ripening period so that the vine funnels more of its limited resources into developing grape clusters.

I enjoyed the gardens of the Napa Valley as much as the wine tasting. White Japanese anemone, pink sasanqua camellia and oakleaf hydrangea are all blooming. The dogwood trees are budded for next year's show and the Japanese maples are starting to color.

It's interesting to know that one grape vine produces about 4-6 bottles of wine per year and in 1968 the nation's first Agriculture Preserve was established to protect open space and prevent future over development.

 

Gardening Tips for August & IPM

I go out into my garden and look around daily. I pick basil for tonight's bruschetta, parsley for the potatoes and a few Sungold cherry tomatoes that don't make it into the kitchen but are eaten on the spot. I count 10 hummingbirds around my 3 feeders, the Ruby-crowned kinglets are scouring the trees for spiders and other bugs and the Wilson's warblers have found the thistle sock.

But what's this? Some of the fuchsia leaves and buds are curled, there are notches in the impatien balfourii and I see white furry things on the trunk of the crabapple.  The weather is hot one day and foggy the next. Better adjust my watering schedule, too. Whether you're seeing some of these same problems in your garden or have different issues that you don't know how to handle, here are some tips to help you decide what you can live with and what you can't.

Integrated pest management or IPM is a fancy name for common sense. By planting the right plant in the right place you can prevent most pest infestation. Pick your battles.Take action against insects only when they pose a significant threat to your plant.

Plants can usually survive with a little bug damage. Insects that are natural predators often will eventually arrive and handle your bug problem.  Picking them off by hand or spraying them off with water often works, too. Some vegetable plants may need to be protected with insect barriers or row covers. Simple traps for earwigs, slugs and snails are effective, too. Vacuuming is another method of controlling pests. Tilling the soil often disrupts the breeding cycle of insects like the rose slug. Encourage beneficial insects to visit your garden by planting a variety of plants. Use natural biological insecticides like Bt and nematodes that have minimal environmental impact.

If you feel you must spray for soft bodied insects like mites, choose insecticidal soap. This may sound strange but by not killing all the pests there will be some left in the gene pool that are not resistant to the organic or chemical sprays. Those left will dilute any resistant genes that appear.

Regular monitoring is the cornerstone of IPM. This is where that daily walk in your garden with a beverage comes in. You can see if a problem is getting out of control or not.

The fuchsia gall mite is one problem that I keep tabs on or the hummingbirds aren't happy. If your fuchsias aren't blooming and the leaf tips look curled up and deformed, your plants are infested with fuchsia gall mite.  First discovered on the West Coast in 1980 it is often mistaken for a disease because of the way it distorts and twists fuchsia leaves and flower buds.  The damage caused can be debilitating.  The leaves curl and distort so much that normal photosynthesis is disrupted and weakened plants fail to bloom  Infested plants usually recover if further mite damage is controlled.

Prune off all distorted foliage and buds.  This may be the best method of control as petroleum oil or insecticidal sprays need to be made every 4-7 days to disrupt the mite life cycle and will result in the mites becoming resistant. Neem oil is not recommended for use on fuchsia flowers.

There are several gall mite-resistant fuchsias, both hanging and upright, that are every bit as showy as the traditional fuchsia varieties.  if you have been plagued by fuchsia mites, try growing one of these instead. A list from Crescent City Fuchsia growers is available at http://www.ccfuchsia.net/ccfuchsia5.htm.

If you have a problem in your garden and don't know what to do, feel free to email me. I'm always happy to help a fellow gardener.