Your garden winds down. Japanese Beetles, Part 1 by Arlene Rowe.
Greetings fellow gardeners,
The weather is starting to change, and you can feel fall in the air. Now is the time of year to be aware of the temperature. If you think it will be cold overnight, cover your tender plants against the frost. If your plants are planted directly in the ground, they are more susceptible to frost than the plants in a pot. You have worked hard for your garden; it would be a shame to lose it to frost. Always err on the side of caution.
This is the first year that I have grown orange cosmos. They are a treat! If you want more flowers on your cosmos and other annuals be sure to take off the spent blooms, but leave a couple to collect the seeds. If you want to collect seeds be sure it is a dry sunny day. If your seeds are wet, they can get moldy.
Orange Cosmos with Hummingbird Sage
You will also notice that many of your vegetables are starting to go to seed. Lettuce bolts upwards and small yellow flowers appear. If you are growing heritage lettuce the seed will come true but with hybrid lettuces, you may not get the same lettuce. Try collecting some seeds as an experiment.
Cucumbers and zucchinis are winding down unless you have some later plantings. Be careful as now is the time for a second flush of cucumber beetles. If you have had cucumber beetles be especially diligent in your cleanup of the area this fall. Do not compost anything you suspect might be harboring the beetle. Use your green bin. Dig down and check the soil in the area where the cucumber beetle has been. You do not want them to overwinter.
Last week we discussed tulips and daffodils, the backbone of your bulb order. You might find it fun to try something a little different this year as well. Hopefully, some of these fascinating bulbs are still available.
Fritillarias are so amazing. They look exotic and flower a bit later than your other bulbs. Apparently, moles find them repellant so that is another bonus. Be sure to plant them according to the directions. The fritillaria that I have is covered in polka dots!
Fritillaria with Daffodil
Alliums are wonderful in your garden. There are so many cultivars from early to late blooming with round heads of various sizes. Onions and garlic are in the allium family as well. Deer and squirrels are not crazy about these bulbs, so you have a better chance of holding on to these plants.
How are your tomatoes? This is the time of year when you find your tomatoes are taking longer to ripen. That is normal. The number of daylight hours are decreasing, and we do not have the same level of warmth. There are many things that you can do for green tomatoes. At this point I would leave them on the plant as long as the weather is favourable, where they will eventually ripen. If you want to try to ripen them inside do not put them in the fridge. Putting tomatoes on the windowsill is a longstanding solution, but the tomato should be showing signs of turning colour in order to have success. And then of course there is the joyful solution of green tomato relish or fried green tomatoes. A culinary delight!!
Have a wonderful week, deadhead your flowers, water those pots and enjoy the cooler weather. Judith (Email: lapisdragonarts@gmail.com)
All Veggie Bites are available at the SGHS website: https://sites.google.com/site/sghortsoc/.
Arlene Rowe has been researching Japanese beetles and is going to share her findings with us. These horrible pests are becoming a hazard in our gardens.
Japanese Beetles (Part 1) (Popillia japonica Newman)
Arlene Rowe
It finally happened: an infestation of Japanese Beetles! I had heard people complaining (wailing!) about these, and I knew that it would only be a matter of time before I would be hit. I thought it would be useful for my fellow gardeners to learn from my experiences as I battle to save my roses. This will be a two-part article; first part, contains the technical details (not too technical though) and then the second part, will chronicle my approach to the problem. This is a personal odyssey for a gardener who has a full-time job and a dozen vulnerable roses.
I have faced a similar challenge when the Scarlet Lily Beetle (Lilioceris lilii) appeared and started to annihilate my Tiger, Oriental and Trumpet lilies. I managed to develop a control strategy that permitted me to keep my lilies while many gardeners gave up. This strategy involved understanding the pest, exploiting its vulnerabilities, soliciting the help of natural allies and using good horticultural practices. It took me about four years to truly get the population under control. I expect (hope?) a similar timeline for this latest challenge.
The first step is: Know the enemy!
Identification
Adult Japanese beetles (1/2-inch-long) are metallic blue green with coppery wing covers. These large shiny beetles came to North America from Japan around 1916 and have been spreading north and west ever since. The adults eat flowers — roses are a favourite — and strip the leaves of over 200 different plant species, leaving behind only veins and stems. The larvae are plump, white grubs (3/4-inch-long) that feed on the roots of a large number of plants, but are especially injurious to lawns, which show irregularly shaped patches of wilted, dead or dying grass.
Life Cycle
Adult Japanese beetles emerge from the soil in late June or early July, begin flying when the temperature is about 21°C, and reach their peak in late July and August. Their normal life span is from 30 to 45 days. They fly to certain plants where their pheromones tend to bring them together in groups or clusters. They will be most active on days that are sunny and warm.
Once the feeding and mating is in full swing, the mated female beetle begins to fly to the soil to lay her eggs and then back to the plant material for food. With each trip to the ground, she will lay only a few eggs, but the routine is repeated over a 6 to 8-week period, until she has deposited about 50 to 60 eggs. Female beetles prefer to lay their eggs in lawns growing in full sun and in sandy soil -- this is the description of a typical suburban lawn. The patchier and more open the lawn (often the case in sandy soils), the better they like it. They don’t particularly like dense green lawns or tall grass. The building practise for modern suburbs is to strip the land of the topsoil (to be sold separately) and build on the subsoil. Then they add less than an inch of topsoil to lay the sod on. The sod very quickly consumes the topsoil, and this leaves the usually sandy subsoil close to the surface. In short, the suburbs are the ideal Japanese Beetle nursery.
The eggs are not left to the elements but are deposited in the soil where they usually hatch in one to two weeks. Newly emerged grubs that have just left their egg stage begin to feed on organic material near the surface of the soil. This is the stage that is easiest to control. The grubs are tiny, very close to the surface, and vulnerable to parasitic and predatory controls.
The young larvae feed on roots until cold weather arrives, during which time the grubs have gone through their first two moults and become significantly bigger. By late September and early October, most of these grubs begin to migrate deeper (8- 14 inches depending on the winter temperatures) into the soil where they will hibernate for the duration of the cold winter months. They are in their third instar during the hibernation period. A really cold winter can seriously deplete the population, which can explain the fluctuations in infestations.
As the ground and air temperatures rise in early spring, the white grubs once again begin to move, this time towards the root system of your lawn. This movement coincides with the greening up of turf grasses and other plants. When they reach the roots, the feeding begins anew.
Once the Japanese Beetle grubs have finished their final active stage of development, they will pupate in cells that are about two to four inches deep in the soil. After a couple of weeks in their pupal cells, newly formed adult Japanese Beetles emerge to begin the cycle all over again.
Fortunately, there is only one generation per year, unlike the scarlet lily bug that could have two generations in 1 year. The beetle's life cycle requires two years to complete.
Eating Habits
At last count, Japanese beetles were known to prey on more than 300 plants in North America. They like to eat starting at the top of their food source and work their way down, as they prefer sun to shade. They feed on the upper surface of leaves which results in a scraped or skeletonized appearance and on the centers of flowers, robbing pollinators of nectar.
Here are just a few of the well-known plants that are susceptible to Japanese beetles (those capitalized are their absolute favourites!):
Flowers (Althaea, cardinal flower, clematis, evening primrose, dahlia, gladiolus, geranium, hibiscus, HOLLYHOCK, morning glory, peony, ROSE, zinnia, canna lilies)
Fruit and Berries (Apple, apricot, cherry, crab-apple, GRAPE, hawthorn, peach, plum, red raspberry)
Herbs (Basil)
Trees (Horse chestnut, American mountain ash, Birch, Linden (American, European), Maple (Japanese, Norway), Pin Oak, Walnut (Black), Willow)
Vegetable (Asparagus, BEANS, rhubarb, soybean, sunflower, sweet corn)
Summer Sweet
Virginia Creeper
Interesting fact: Within 30 minutes of consuming geranium petals, the beetle rolls over on its back, its legs and antennae slowly twitch, and it remains paralyzed for several hours. The beetles typically recover within 24 hours, but they often succumb to death after predators spot and devour the beetles while they are helpless.
Control Methods
Listed below is a summary of the major control methods that are available:
Good Horticultural practices: Keep your lawn tall (3-4 inches) before the annual July heat. Add compost to the lawn ever year to help build up the soil base and make the sandy subsoil unavailable to the female beetles.
Avoid night lighting: The light attracts Japanese beetles just at the right time for egg laying: it’s like telling them: dig here! Use just enough lighting for safety purposes and try not to direct any towards the lawn itself.
Hand-Picking: Hand-pick the beetles off your plants and dispose them.
Parasites: Introduce parasitic organisms to attack the beetles, including nematodes, the milky spore bacterium, certain tachinid flies and tiphia wasps.
Organic sprays: Spray the plants with a botanical insecticide, such as neem oil or insecticidal soap.
Create a barrier: Use row covers over ground crops during the 6- to 8-week feeding period.
Domestic Animals: Certain domestic animals are also known to be voracious beetle eaters, including chickens, ducks and guinea hens.
Wild Animals: Many species of wild animals also will eat Japanese beetles. Wild birds known to eat these beetles include robins, cat birds, cardinals and especially starlings. Mammals –- namely raccoons, skunks, moles and shrews — will eat beetle grubs.
Companion plants: Incorporate plants that repel Japanese beetles such as catnip, chives, garlic, odourless marigold, nasturtium, geranium, rue, or tansy near susceptible plants to help keep the beetles away. Mix clover into your lawn or even replace your lawn grasses with a clover lawn.
Japanese Beetle traps: Do not!! use Japanese beetle traps which you can buy at any garden supply store. Most Japanese beetle traps contain two chemicals to attract beetles, a sex pheromone and a floral lure. Japanese beetles are attracted to the trap in larger numbers and move right onto your garden.
Plant Japanese Beetle resistant plants: Avoid planting the beetles favourite food sources.
Retail Pesticides: Any pesticide that is effective will contain one of these banned active ingredients (carbaryl, acephate , imidacloprid or permethrin).
The bad news...
No one control method is the perfect method to control the beetles completely, except maybe, replacing beetle favorites with plants they simply don’t eat. And there is no guarantee that the beetles won't develop a taste for these in the future. Note, I said control since you can't (and probably shouldn't) eradicate them. Why? Unlike other infestation like aphids, the beetles are very mobile, and they can travel for miles. If anyone in your neighbourhood has problems with the beetle, you will eventually have it too. And if you are in the suburbs, your lawns are beetle heaven.
The good news...
By carefully combining different methods, you can reduce the population to the point where the beetles become more a small inconvenience than a scourge. This selection will depend upon which ones interrupt the beetle's life cycle most effectively, do the least damage to you landscape and fits your gardening habits since consistency in application is the key to success.
There are excellent websites about this pest but bear in mind that many of them are located in the United States and the controls available, and timing, will be different. In addition, the climate is getting warmer (Ottawa has moved from Zone 4b to 5b in the last 20 years) and some of the information on the websites is out of date.
In the next article, you'll see what I have done and am doing to save my roses.
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