Fall Readiness Part III - I Spy Pest Insects, Lots of Them!

All of a sudden they were there, what you ask? Small, black spotted flying objects that sprang and darted continuously among the vegetable plants, nearby roses and annual lantana. Are these miniature UFOs (which have been in the news of late)? Maybe the UFOs released these yellow and black spotted beetles on a quick fly over the Front Range?  Something isn't right here. My mind isn't ready for a spotted yellow beetle infestation this late in the growing season. I just want to pluck more ripe tomatoes for next week's salads and sandwiches before the white flakes fall from above!

The flying yellow objects are spotted cucumber beetle, also known as southern corn rootworm, proper scientific name is Diabotica undecimpunctata howardi. 

No doubt you've seen one or five on your cucurbits (cukes, pumpkins, squash, cantaloupe, watermelons) over the years, but nothing like the scores that have been flying these past couple of weeks. I couldn't take them anymore (or eat anymore yellow cucumbers, a banner, delicious year for sure), so I cut, dug and tossed the vines this past weekend. The Italian striped zucchini is harboring these pesky pests too, but I can't bring myself to pull the plant. Soon.

A third inch in size, adult beetles overwinter outside in protected sites. When temperatures warm up in spring they start moving around and laying eggs near their favorite cucurbits. Eggs become larvae, pupae and adults in only fifteen days. In Colorado we have at least two summer generations. Adult beetles chew on a wide range of ornamental leaves and flowers.

There are some ways to battle these small flying pests, but at this late date in the season, it's probably best to just let them play out their existence (I am). Next year consider some of the cultural techniques if you wish. Sprays generally don't work all that well and why not let any natural predators get them on their own. Use of chemical sprays upsets the balance of allowing beneficial predator insects free reign to seek and destroy their pest for a quick meal. 

Here's a list of controls to consider next year - taken from the Department of Entomology in Washington State. Click here to read the full article with more information.

• Natural predators to spotted cucumber beetles include wolf spiders and ground beetles. We have both here in Colorado. 
• Rotate your crops each growing season so pests don't get accustomed to the same place to dine. The beetles can still fly, so this isn't a guarantee, but still wise to rotate yearly.
• Try using transplant cucurbits instead of direct seeding (I know, these crops are SO easy to start from seed directly in the garden spot where they will grow). Transplants lessen exposure to cucumber beetle feeding when they are just ramping up for the summer. Also delay transplanting until later or mid-summer when these pests are out hustling earlier planted cucurbits in other gardens.
• Use the lightest weight floating row covers to prevent beetle access to your plants. When plants start flowering, remove the covers so bees can get in and pollinate.
• Use weed and herbicide-free straw mulch to prevent beetles easy movement from one plant to another. Straw also helps conceal and protect predator wolf spiders. As straw breaks down over the summer it helps with the springtail population which also feeds wolf spiders. 
• Metallic colored mulch has been shown to repel beetle feeding.
• Plant resistant vegetable varieties.

Other Resources:

Cucumber Beetles University of Minnesota

The Spotted Cucumber Beetle Colorado State University

Utah State Striped and Spotted Cucumber Beetle includes resistant varieties

Spotted Cucumber Beetle on Annual Lantana

Fall Readiness Part II - Japanese Beetle Edition

The weather will be cooling off soon, let’s hope we catch up this fall on much needed precipitation. What about the bugs—specifically the Japanese beetle that rampaged ornamental plants in several Front Range neighborhoods and pained the souls of thoughtful gardeners from July to September?

Online Photo from bioadvanced.com

Thankfully adult Japanese beetles die off each fall after their one-year life cycle from egg, larva, pupa, to adult. Gone, but not forgotten—they leave next year’s army of plant eating progeny all over the neighborhoods they visited. Right now, their offspring (white grubs) are deposited in fields, pastures and lawns in home landscapes, parks, schools, golf courses, even cemeteries. 

Each female Japanese beetle lays between forty to sixty eggs in her short summer life of eight weeks or so. When totaling the hundreds to thousands of Japanese beetles in yards, that's quite a few eggs!

Females prefer laying eggs in lawns or fields near her feeding source. Cool season lawn grasses including Kentucky bluegrass, perennial ryegrass and tall fescue, which are most common in Colorado, are preferred hosts for egg laying. 

Some warm season grasses like Bermuda grass and buffalograss are less favored for egg laying. 

Once eggs become larvae, also called white grubs, they become grass and plant root eating machines for sustenance—well into October.

If white grubs are numerous, lawn damage generally shows up in August to October in the form of patchy dead areas. If severe, the dead grass can easily be rolled back like a carpet to expose eaten turf roots. High numbers can also attract foraging animals like racoons, squirrels or birds that happily dig up lawn areas in search of a white grub meal.   

White grubs in lawns are mostly inactive from late fall until the soil warms up in spring when they resume feeding. They survive all types of winter conditions and shouldn’t be expected to be killed off by cold or snowy weather. White grubs will move deeper when it gets colder or drier, but generally reside four – six inches below the soil. They transform to the pupal stage in spring (usually in May) and emerge as adult beetles from lawns sometime in late June or July to begin another season of plant eating carnage. 

What Now ...

Recommended controls to kill white grubs in lawns are all about timing. Products generally require one summer treatment and are most effective when applied from May through August. Treating lawns isn't one and done forever, lawns needed to be treated every summer.

There are a couple of products to consider applying right now while lawns are still warm, but don't wait much longer. If you miss the windows to apply lawn products, your best bet may be to wait until next summer.

Two effective biological (organic) controls for lawns include beneficial nematodes (microscopic worms) that reproduce inside the Japanese beetle white grub causing them to die within a few days and a bacterium stomach poison called grubGONE! that kills larvae. Choose one or the other.  

Beneficial nematodes need to be mixed and then sprayed on the lawn using a hose end or pump sprayer. Easy to follow mixing and spraying instructions are on the package. Your local independent garden retailer (not box stores or mass merchants) carry beneficial nematodes (refrigerated). They must be the heterorhabditis bacteriophora strain, which will be well labeled on the package. 

GrubGONE! is another organic product that is very effective in killing white grubs in lawns and is very safe to use around people, pets and pollinators. Just add the granular product (based on your lawn square footage) to your fertilizer spreader and water it in. Also purchase grubGONE! at local independent garden centers or online.  

Check out this very informative fact sheet on Japanese beetles in Colorado from Dr. Cranshaw at Colorado State University at http://extension.colostate.edu/docs/pubs/insect/05601.pdf. He includes detailed information about control products, trade names, timing and helpful comments. 

Also check out my Japanese beetle website for additional information, look for my 2020 classes on Japanese beetle management which will be posted later this fall. 

The Summer that Was and Fall Readiness - Part 1

June 22, 2019 Covers, Nighttime Temp 45 degrees

The spring and summer growing season of 2019 may be one for the books. Late spring frosts and cold temperatures delayed May planting. There were many return visits to garden centers to replace tomatoes and petunias that didn’t survive May and June nights in the forties. 

 

Gardening weather was good for about a week in June until summer turned stifling hot in late June and remained mostly dry and hot through August. It’s still hot.

Hail events decimated annuals, many perennials, tomato plants and cars. Some gardeners threw in the towel and relied on produce donations from others. Others had a tremendous summer crop of green beans, peppers and squash. The mantra that “there’s always next year” was heard often.

Fall arrives on September 23. Let’s see if sweater weather and orange shades arrive too. Trees in the high country are already turning. Some urban trees look like they already have started changing colors, but on closer examination are those in fact scorched, dead leaves? 

5-27-19 Middle of the Night Hail Damage on our Garlic (sad)

How are your trees doing? Have you taken a close look at them lately? Are they ready for the fall to winter transition? Year after year trees that consistently go into winter with dry roots often resulting in leaf scorch, early leaf drop, canopy die back, or possible death. 

   
Please don't assume that trees will take care of themselves from automatic sprinkler systems, the occasional drink from summer rain storms or when fall and winter moisture arrives. That may be true for well-established very drought tolerant trees and plants—which wise gardeners have chosen to plant. 

The reality is with our low average yearly moisture (12 – 14 inches), trees often need our help - especially in a low moisture season like this one. So far this year we’ve only had eleven inches of moisture. Simply put, our trees and possibly many plants in our landscapes are drought stressed. 

Plan on year-round watering practices. This is especially important for new tree plantings. Regularly check soil depth to see that tree roots are moist to a depth of eight to twelve inches (poke down with a screw driver or invest in a soil probe). The exception to watering is when there’s snow on the ground, cold temperatures below forty degrees or frozen soil. Our vital tree landscape is counting on us!

New Trees Need Winter Water when Moisture is Scarce!

Fall and Winter Tree Watering—

• Plan on deeply watering established landscape trees, including conifers, at twice a month now through November, or later if it stays warm. Newly planted trees need watering more often—two to four times a month. 
• From December through next spring, when temperatures are above forty degrees and there’s no snow cover, water established trees once a month mid-day. 
• After sprinkler systems are turned off connect the hose to a sprinkler. Place the sprinkler head under the outer branches (dripline) and move the sprinkler about every ten minutes, or less if water is running off. Water around the full canopy of the tree, then move on to the next tree.
• Insert a long screwdriver into the watered area and check to see if moisture has penetrated at least 8 – 12 inches. 
  

General Landscape

• Indoor plants that have been growing outside need to go indoors before nighttime temperatures remain below fifty degrees. First get them acclimated to lower light conditions by moving them to shady areas for several days. 
• If possible before their return indoors, lift the plant from the container and check the rootball for hitchhiking insects. Treat with insecticidal soaps or systemic (soil) products for scale insects, white fly and spider mites. Remove damaged or leggy growth. Repot overgrown plants to a slightly larger container. Give them a light fertilizer. Yellowing or leaf drop is normal until plants get used to being indoors again. 
• To extend the vegetable growing season be prepared to use frost blankets or lightweight sheets over warm-season crops when nights are below fifty degrees. Cover plants all the way to the ground to trap warm air. Avoid using plastic directly over plants as it transfers cold to the foliage. Remove covers when temperatures reach fifty degrees.