PUNCH LIST: How to handle Japanese beetles
Enjoy regular strolls through the garden? Might as well remove spent blooms, pull weeds and plan. “A garden is never so good as it will be next year” said Thomas Cooper, a 19th-century philosopher.
In the landscape
•Take photos of your garden this month to help plan for future additions, changes or reminders of summer blooms and time spent outdoors.
•Often indoor houseplants take a back seat to care during the summer. They always appreciate an overhead shower to clean the foliage and reduce any spider mites. While on vacation, increase humidity by moving plants close to each other and placing a gravel tray covered with water under plants.
•Weather and proper cultural care make a huge difference with crop successes and challenges, especially tomatoes.
•Hot days (in the 90s) have presented challenges, including blossom drop and less fruit on the plants.
•Some areas have been hit regularly with heavy July monsoonal rains may be dealing with waterlogged soils.
•Cat faced, growth cracked or misshapen fruit is common after fast growth during dry weather followed by too much irrigation or natural rainfall. Early ripening fruit is most affected and, if not too damaged, should be OK to eat when ripe. Later summer and fall maturing fruits are usually just fine.
•Environmental factors including heat, drought, wind or uneven watering can cause tomato leaves to curl or twist. No treatment needed; just maintain good cultural care. Other leaf-curl culprits include herbicide drift or possibly a virus. Viral-infected plants need to be removed to prevent spreading to other plants.
•Fungus issues like early blight are generally more common on tomatoes than bacterial diseases. In some years, like this one, both can be present. They have similar looking leaf symptoms: lower-leaf yellowing and brown to black spots.
•Take photos of plants or bring some leaves and fruit to your local Colorado State University Extension office or knowledgeable garden center for diagnosis of tomato issues or diseases.
•Good cultural care includes mulching to prevent soil splash back on the plants and avoid working in the garden when plants are wet.
Battling Japanese beetles
•Given free reign, adult Japanese beetles will skeletonize or eat entire leaves, buds or flowers of roses, Virginia creeper, dahlias, grape, green beans, linden and apple trees and scores of other landscape and agricultural plants.
•They have moved in to new areas of metro Denver this summer.
•Japanese beetles have a 1-year life cycle. Timing is important for reducing adult and larvae numbers, which means less plant damage and hopefully fewer beetles next year.
•Their offspring — eggs/larvae/pupae — are being laid now and will live below and feed on grass turf through next summer, when they emerge as adults.
•Even though adult beetles can fly up to 5 miles from other yards, parks and businesses, consider treating your lawn while females are laying eggs (next year’s generation).
•Large numbers of larvae may harm or kill grass turf.
•Many insecticidal control products are available and are very effective on grubs. Biological alternatives using parasitic nematodes or milky spore bacterium are additional options to consider.
•As grubs get larger in the fall, control products are not as effective as treating lawns early in the season. So do not wait — apply controls now.
•Culturally the lawn can be made less desirable to females during the summer egg-laying period. Keep the lawn drier and taller.
•Research on Japanese beetles confirms that removing adult beetles reduces further damage to plants and increases the attractiveness of the plants. As volatile compounds are released from chewed plants, the more beetles are attracted to those plants.
•Reduce adult beetle numbers by tapping them into a jar of soapy water early or late in the day, when they are slow-moving.
•It is OK to squish beetles. The research says that upon emergence from the soil, female virgin beetles are quickly mated. After mating they no longer have the much-sought-after scent that draws more beetles to the area.
•Traps are not recommended to reduce numbers; they attract more beetles to surrounding plants. If your neighbor is using a trap, you may have fewer beetles coming to your yard.
•There are several insecticidal spray control options for adult beetles. Use care; read all labels and never apply when bees, beneficial insects and pollinators are active in the area.
•Read more information including suggested control products on this helpful fact sheet from Colorado State University: http://extension.colostate.edu/topic-areas/insects/japanesebeetle-5-601/
Adult Japanese beetles will devour entire leaves in the garden. Here they're shown on hibiscus.