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Archive for the ‘Bad bugs, icky diseases, and operator error’ Category

The first of the aphids showed up in November, a small herd of them clustered on the soft, succulent tips of the hibiscus plant overwintering in the sunny window of the back room. My spouse was concerned, but I pooh-poohed this, saying I’d pick up some insecticidal soap to get rid of the sucking pests.  “A couple of spritzes and they’re out of here,” I said.

Mother Nature loves overconfidence, especially in gardeners who routinely try to bend her to their will. She clearly loved the challenge I threw down, because the aphids she sent to worry my plant are imbued with a resilience and will to conquer that would please any conqueror of yore.

As soft bodied insects, aphids are vulnerable to soaps; it disrupts their exoskeleton and causes catastrophic water loss. In order for it to work, the soap has to coat the body of the bug, so spraying the entire colony is a must to ensure control of the pests.

If you miss any aphids, they’re bound to bounce back quickly. Aphids are parthenogenetic; they can produce offspring without fertilization of eggs.  They’re also viviparous, hatching eggs within the mother’s body and birthing live young.  The young are almost always daughters, who, at the time of their birth, are already maturing their own eggs for offspring.

They’re all girls, nearly all the time, and are born pregnant, which is why their numbers increase alarmingly fast. Nymphs are mature enough to produce their own daughters in an average of 10 days, under good conditions such as a warm place with no predators.

This is exactly the condition in our back room, something that in my overconfidence I failed to take into consideration. Casually, I sprayed the colonies at the tips of the plant.  A few weeks later my spouse asked when I was going to get the soap to spray the aphids, and, puzzled, I said I’d already done this.

“Really? It didn’t work,” he said, calling me to the back room to behold colonies covering both tips and budding flowers.  I sprayed again, to the same results: the soap knocked back some of the aphids, but the colonies returned with greater vigor in a few days.  Muttering and calling the beasts unpublishable names, I attacked again, and again, employing soap and hand swipes to rub the bugs away.

The battle seemed lost, until one day a sight stopped me as I raised the soap bottle. A ladybug, perched atop the uppermost growing tip, snacking on aphids as if they were cookies.  We welcomed this beetle like an honored guest, the two of us hovering and watching her feed.  “Will she get all of them?” My spouse asked, eyeing a bud with a particularly large number of aphids.

She got through quite a few of them, but she didn’t stick around; after her snack she seems to have settled back into the mulch in the pot to continue her off-season rest. We look for her daily, and considered purchasing more to help her out.

But ladybugs come in bags of hundreds and our house is too small to host them; my imagination had them raiding our meals once the aphids were gone in a manner much like the zombie hoards on TV. Other biocontrol options are even less appealing, such as releasing parasitic wasps.  Although they’re helpful in reducing aphids, swarms of wasps aren’t exactly a welcome mat to visitors.

The aphids are still there, but fewer in number; my routine of spritzing them with soap are keeping them at bay until the ladybug reappears. This balance is a good one, and we wait for warm spring days when the ladybug reappears to help out.

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In the warmth of our early spring, landscapes burst with enthusiasm for the season; trees and perennials woke up in a raucous, flower-filled welcome.  Gardeners greeted the spring show with joy, but as plant after plant sent forth blooms we soon went from feeling euphoric to feeling alarmed.

“Wait, wait, it’s only March,” we muttered at forsythia, and “you’re not supposed to be here until Mother’s day,” we told lilacs.  Crabapples ushered in April instead of May while flowering bulbs burst open in a display more like the fireworks finale than a long, colorful parade.

Sure, it was nice, but also disturbing.  After all, Mother Nature has a way of laughing at Colorado.  And this year, she’s in a full belly-laugh, sending snow and freezing temperatures just as we brought out our Hawaiian shirts and flip flops.

The start of our season was weeks ahead of schedule, with horticulturists and gardeners noting a three-week earlier flowering or leafing out.  Diseases and insects emerged early too, making things busy for landscape and tree maintenance companies.

Experts use phenology, or Degree-day models, to predict pest outbreaks; it’s based on the number of days or hours at certain temperatures the pest needs to emerge after winter.  Depending on the pest, we’re eight days to one month ahead of the usual pest problems.  The Emerald Ash Borer began popping from trees at the beginning of May; last year (the first season tracked following its detection here in Colorado) it emerged in early June.  The bug isn’t getting more aggressive, it’s simply following the climate we’ve had this year.

Gardeners should be aware that many pests are active earlier.  And although the recent cold weather might have put a crimp in their activities, those pests are resilient.  Controlling pests before their damage is severe is the best way to sustainably garden, so be on the lookout for potential problems and have your strategies in place to keep your plants healthy.

Here are a few thugs to watch for:

Fire blight is a bacterial disease that’s destructive to apple, pear, quince and crabapple. It attacks in spring, when temperatures reach 65 degrees F and frequent rain occurs. The best weather conditions for this damaging disease is exactly what we just had: humidity, rain, and hail.  This is when masses of bacteria are forced through cracks and bark pores to the bark surface, where they form a sweet, gummy exudate called bacterial ooze.

Insects attracted to this ooze pick up the bacteria on their bodies and carry it to opening blossoms or young branches wounded by pruning, insects, or hail. Girdling cankers – areas of disease on the wood – develop from branch or blossom infections.  Leaves wilt, darken, and curl into a shepherd’s crook. This gives the tree a fire-scorched appearance, thus the name “fire blight.”

There’s no cure for this disease; prevention is the best solution. Fire blight control include use of resistant varieties, cultural practices, pruning and spraying.

Japanese beetles are beautiful but devastating insects that attack over 300 types of plants, including grapes, raspberries, beans, apples, and roses.  Ganging up on plants, they cause serious injury.  Louisville, Lafayette, and Boulder residents have reported the beetles; it’s unclear how widespread they are in our area.  For more information on Japanese beetles and their control, see ext.colostate.edu/pubs/insect/05601.html.

Gardeners with strawberries, raspberries, and other cane fruit should watch for Spotted Wing Drosophila (Drosophila suzukii).   The overwintering females of this fruit fly relative lay hundreds of eggs on ripe fruit.  Upon hatching, the larvae burrow inside, where they feed on the fruit, growing into plump maggots.  According to the Degree-day models, we’re rapidly approaching peak egg laying by overwintering females and the first emergence of this season’s adults.

From egg to adult is a mere eight to ten days, depending on temperatures, and there are several generations per year.  Keep your fruit meticulously cleaned from the floor of the garden and pick and discard overripe fruit.

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EAB PA DCNR  Think our recent cold snaps might halt the Emerald Ash borer in its tracks? Not likely, according to the United States Forest Service. Even though the polar vortexes are creating havoc on our landscapes, one place that’s still cozy is deep inside the wood of trees.

For the cold to smack the Green Menace down, temperatures have to dip to at least minus 20-degrees F inside the wood, and even colder temperatures are needed to kill higher numbers of larvae. Boulder hasn’t seen those types of low temps, so don’t count on Mother Nature giving the cold shoulder to the emerald pest this winter.

Read their report on how cold temps help stop the bug.

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Doing battle with a bug threatening to destroy thousands of our trees takes patience, strategy and a variety of tools. You can throw thousands of staff hours at it. You can remove hundreds of infested trees. You can even sizzle the invaders with electrified, bug-zapping replicas of the female emerald ash borer (though effective on a testing scale, I can’t envision stringing thousands of lines of the shocking beauties throughout the trees).

But sometimes what you need is an answer both subdued and eloquent, another bug to target a thug that’s attacking our ash. Dubbed the “Green Menace,” the emerald ash borer (EAB) has been found in Boulder, and Colorado’s interagency EAB Response Team is pulling out all the stops to try and halt the spread of the insect.

With that in mind, they’re releasing wasps, but not the kind that disrupt picnics or carry toddlers off for a midnight snack. These tiny insects are harmless to humans and beasts; they’re stingless and don’t concern themselves with picnics or soda pop.

Instead, Tetrastichus planipennisi target EAB larvae as they grow under the bark of the tree, laying eggs inside their bodies for the hatching wasps to use as hosts. The growing parasitoid larvae ultimately kill their EAB hosts before they can mature. Each female wasp can lay up to 100 eggs in a single larva. 

Tetrastichus planipennisi  pupae

Tetrastichus planipennisi pupae

 More than two thousand of the wasps have been brought to Boulder already, and released through the combined efforts of the Colorado Department of Agriculture, University of Colorado, City of Boulder and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). For years, USDA has been employing biocontrols for use against EAB in the U.S., and they are providing the wasps at no charge to Colorado.

There are moments during which I suddenly have soundtrack music cue up in my head, and in this case, the snippets of the William Tell Overture distract me as I contemplate what the wasps will do. But the release itself is a tad anticlimactic: no one screams “Release the wasps!” while swarms of adults cloud the skies. Rather, the release is a quiet one; the wasps rest in their pupal stage, nestled together in wood bolts attached to trees. They’ll gradually chew their way out and fly to find their prey, quietly doing what many of us cannot: finding EAB larvae.  Climbing

It is hoped that the wasps will help suppress EAB populations in the city and manage the insect’s potential future spread, much like a hero arriving to save the day. The wasps have been released on the East Campus of the University of Colorado, in a location that offers the wasps rich hunting, as ash in this area are hard-hit by the bug.

According to a press release from the EAB Response Team, up to two additional Tetrastichus releases are planned in Boulder in the coming weeks, dependent on weather conditions. The parasitoid wasp Oobius agrili, which targets Emerald Ash Borer eggs laid in the late spring or summer, also is being considered for release here in 2015.

Like EAB, Tetrastichus is native to Asia and the USDA conducted extensive research on it in its native range before bringing it to the U.S. for testing. Once here, they conducted further testing to ensure that the wasps won’t attack other insects in the absence of EAB. They determined that the wasp prefers to hunt EAB above all else, and even if they lay eggs on non-EAB larvae, the eggs don’t survive. Due to this, the USDA determined that Tetrastichus poses little risk to other insects here.

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Mantis religiosa. Lisboa, Portugal.

Image via Wikipedia

Attending the Larimer County Humane Society’s Top Cat and Tails gala, I was impressed by the devotion humans feel toward animals and their creative ways to raise money to care for them. The live auction had many items of interest, from Caribbean condo stays to baskets of wine, but what captured my fancy was the offer of having your pets’ photo plastered to a billboard. For the right price, Fluffy will be the spokes-animal of an adoption ad for three months on the highway.

Several of my dinner companions were already shaking their heads before I got the words out, knowing the type of pets I keep. “A tarantula would be perfect for that billboard,” I said, musing on the possibilities. “But right now the only pet I have is a praying mantid. I wonder if that would help them raise pet adoption awareness?” Those at the table who didn’t know me stopped chewing, looking mildly horrified.

“She’d be easy to photograph; her wing is damaged and she can’t fly. That’s why the humans rescued her before giving her to me – they didn’t think she’d survive,” I said, plying their sympathy for a wounded creature. But good intentions took me too far; enthusing about her laying an egg case didn’t elicit maternal ooohs and ahhhs I’d banked on.

“How many eggs are in that egg case?” asked one guest, staring at me as if he were seated with a member of the Addams Family. “About 200,” I said, “but they’re hungry when they hatch and go after each other, so you really end up with about six fat, happy youngsters.” Discussing insects and cannibalism over dinner is one reason why I’m not invited to many formal events.

The insect in question is a European mantid (Mantis religiosa), picked up by well-meaning people who feared for her safety in winter. In this, the good Samaritans are right; these insects, imported for biological control, only survive our winters when it’s mild, although a few of the toughest manage to get through to spring. Thus, the European mantid is found throughout much of Colorado.

It’s a big bug, measuring three-and-a-half inches long, green with a “bull’s-eye” marking under the front legs. These forelegs are spectacular: long, broad, edged in spikes and tipped with claws to hold prey close to feed. “I’ve had mantids I can hear eating, crunching their grasshoppers as they chew through the exoskeleton,” I said. Oddly, this tidbit of information had the table guests looking for vacant seats elsewhere, and my spouse started pressing his knee against my leg in a subtle warning that I was scaring people.

The eggs she laid are encased in an insulated, foamy material that hardens and gives them the appearance of a Styrofoam peanut. Mantids lay these most often on hard surfaces such as rocks, pipes, fences, and plant stalks. In spring, they hatch, and hundreds of mantid nymphs emerge, feeding on soft insects at first, then as they grow, moving on to larger prey.

Should you try rearing mantids at home, keep them in separate terrariums. If you have an adult female, give her a stick on which to lay the egg case, then move her into another cage; egg cases need a cold period and are best stored for a few weeks in an unheated place such as a shed or on the north side of homes. Bring the egg cases indoors to warm them to room temperature and encourage hatching.

Feed the nymphs small insects, such as fruit flies, midges and small flies. As they grow, feeder crickets from pet stores work well. Mantids need water, so mist the interior surface of their container once per week. Release your mantids into the garden once days are warm. But take my advice, and keep your pet information to yourself.

Non-gardeners just don’t understand.

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Melanoplus femurrubrum (redlegged grasshopper)...

Image via Wikipedia

A rustling noise alerted me to a visitor in the squash patch, one that gives gardeners the chills each season. Thinking it was a squirrel, my concern was simply for the swelling pumpkins whose rind is irresistible to the pilferers. Stalking up to the patch to catch the robber red-pawed, the rustling fell silent and no squirrel was found.

Mouse, rabbit and neighborhood cat all went through my mind but it wasn’t until the thief sprang from the foliage that I knew I had a problem. I stared into its eyes as it clung to the front of my shirt, gently masticating the last of its snatched meal. A grasshopper had invaded my vegetables, and where there’s one, there’s bound to be many.

More than 100 species of grasshoppers live in Colorado. Some feed on grasses, others weeds, but the Differential (Melanoplus differentialis), Twostriped (Melanoplus bivittatus), and Redlegged (Melanoplus femurrubrum) are frequent pests in home gardens. All types lay their eggs in the soil, favoring dry, undisturbed locations for their nurseries. Upon hatching in spring the young dine on nearby plants until they reach adulthood and fly off in search of food.

Controls for grasshoppers are aimed at the nymph stages, when the insects are vulnerable and don’t move over long distances. Baits, sprays, or the parasitic nematode, Nosema locustae, that worms its way throughout the body of the bug are all best on younger grasshoppers in early summer.

Now that it’s August such controls are no longer effective, since the hoppers in my yard arrived as adults. The sprays of insecticides that can be used are only slightly effective; they might kill the munching marauder today but have a limited time span. Another hopper will take its place in the next few days.

My usual method for ridding my garden of pests — throwing them in the neighbor’s yard — doesn’t work with grasshoppers; they just bounce right back. Literally. And floating row covers would do more harm than good, since I’d be trapping the hoppers under the tent with a complete buffet at their claw tips.

Poultry are a great choice if you live in an area that allows them. I know this first-hand, since my son used to raise ducks. They were comical, and thanks to a drake who took guard-duck duty seriously, were effective at keeping all manner of annoying creatures out of the yard, including grasshoppers and door-to-door salesmen.

Chickens, turkeys and guinea fowl are also touted by Colorado State University Extension as excellent non-chemical grasshopper control. The first two birds I’m familiar with, but guinea fowl are a mystery. Evidently they look like small vultures wandering your yard, shrilly cackling as they swoop down on insects, particularly grasshoppers, June beetles or Japanese beetles. Guinea hens are noisy, belting out a warning whenever intruders arrive, which in suburbia, means a cacophony arises whenever the postman, meter reader, garbage truck or my mother stops by. The entertainment potential alone makes them worth considering.

Ultimately there is little to be done to rid my garden of grasshoppers. Hopefully the plants

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Photo courtesy of Alison O'Connor

Several years ago a friend gave me hops plants, encouraging me to grow them, not because I love beer, but because I love bugs.  Each year, she assured me, her bines are crawling with ladybugs and lacewings feasting on the aphids that load the leaves. 

 The prospect of such a scenario won me over, and the hops have a home in the garden.  I’ve watched and waited for the insects, but the outbreak of historic proportions never arrived.  Until now.

Cleaning up and trellising the overgrown mass, I got up close and personal with more aphids than was comfortable.  True, they’re soft bodied and not aggressive, but the sheer numbers on the hops is alarming and the longer I worked with the bines, the more aphids I had crawling on me. 

Eventually I had to get the hoard off of me, and the stamping legs, shaking arms, and head flipping made my spouse think my iPod must be playing a rocking tune.  But soon he noticed the moving mass of pale green slowly engulfing me, the fence, and everything else in their path, and rescued me with a series of well aimed thwacks from his gloves. 

We fled the area, telling ourselves that the ladybugs have it under control, but in truth those plants are on their own.  A quick poll of gardeners this season shows many are fighting the same battle against that pear-shaped menace, which are rapidly turning our gardens into the Year of the Aphid.

Aphids are small, soft bodied, sap-sucking pests, and Colorado has several hundred species in a variety of sizes and colors, from green to black, purple, and red.  They feed by treating plants as their own personal big gulp, sucking the sap and reducing the plant’s vigor.  Aphids are born pregnant, and reproduce so quickly they rapidly build up on the plant. 

 But being soft bodied they’re easy to control.  Grab the hose and attach a nozzle that can direct a strong jet of water onto the plant.  The stream rips aphids from the stems.  If they aren’t crushed by water pressure, at least they’re flung to the ground, and due to very poor eyesight, can’t find their way back. 

 Insecticidal soap is excellent, provided the formula is made for the plant it’s sprayed upon.  Always read the label of any spray to see if your plant is listed.  Your plant must be mentioned on the label or chances are something about the spray will harm the plant.

Leaf curl aphids pose a different problem by stimulating the leaf to form a protective tent around the aphid colony.  This is a common problem on ash, plums and viburnums. Within the leaf, the colony is protected from water sprays and insecticidal soap, but there are a few beneficial insects can wriggle in and wreak havoc on leaf curl aphids. 

If you’re brave enough, grab one of the leaf curls and unroll it, ignoring the sticky sap and crushed insects that coat your hands.  Look for lady bug and lacewing larvae, or young syrphid flies, which are maggots.  Not all beneficial insects look cuddly like the ladybug, and learning to recognize pest predators is a must for savvy gardeners.  Check out the photos and information on Colorado State University Extension’s fact sheet .  To encourage beneficials, avoid spraying broad-spectrum insecticides that kill both good and bad bugs.

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