Contents tagged with horticulture

Integrated Pest Management in the Butterfly Haven

Tags: pest management, butterfly haven, horticulture, insects

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Published On 1/15/2013

I'll be honest with you, folks. There's just no way I can keep every greenhouse pest out of the Judy Istock Butterfly Haven. And you want to know something else? I don't particularly intend to.

Now I'm not rolling out the red carpet for aphids here. At least not compared to the hero's welcome they get just by us stocking the Haven with all their favorite foods and a perfect breeding climate. If they were easy to keep out, they wouldn’t be called pests. Aphids, whiteflies, mealybugs, and scale insects can lay waste to thousands of dollars' worth of plants in no time, and then all we'd have is hungry butterflies and some sticks covered in bug poo.

Mealybug Destroyers

I could run around in the off-hours spraying chemicals. I don't because 1. Toddlers (et al) will put anything, including leaves coated in poison, directly into their mouths and 2. Butterflies, being insects, react unfavorably to insecticides. Also, I'd have to get here even earlier in the morning.

But more important than my alarm clock is the fact that we, as an institution, have adopted Integrated Pest Management (IPM) as our strategy for all pests. One part of IPM means using the least harmful means of control first. That would be prevention most of the time. I check plants for infestations before I plant them in the Haven. I monitor the plants already there to catch outbreaks at early levels, and then a little soapy water works miracles. But the true secret, the one that has me smugly unconcerned while hordes of mealybugs roam the streets, is that every now and then I release MORE bugs into the Haven.

We order the workhorses of the Butterfly Haven from Beneficial Insectary in Redding, CA. Ladybugs (Hippodamia convergens) devour most soft-bodied plant pests, and do so as adults and as larvae. This is also true for the similar-looking Cryptolaemus montrouzieri, which goes by the more pronounceable and colorful common name ‘mealybug destroyer.’ I also release three wasps into the Butterfly Haven--all of them completely harmless to humans. In fact, they are all smaller than the stinger of the wasps commonly associated with fear and pain. Being so small I guess they are not worthy of cool common names, but they answer to Aphidius colemani, Aphytis melinus, and Encarsia formosa and they parasitize aphids, scale, and whiteflies respectively. Parasitic wasps lay their eggs inside living hosts, sometimes paralyzing them first, and let their newly-hatched young eat their way out. Some people think that's gruesome, some think it's awesome, some think it's both.

Our workhorse, the Ladybug

Notice how I mention these helpers as adults and as larvae. If I were somehow, magically, able to remove every single 'bad bug' from the Haven, my beneficial buddies would have no food, and therefore couldn't breed and maintain a population. One aphid or scale (both of which can reproduce asexually, which is far creepier to me than the parasitic wasp thing) could turn into millions nearly overnight. Instead we aim to keep the pests at an ‘acceptable’ level, which is another tenet of IPM. Then our beneficial insects have more likelihood of breeding and remaining in the Haven to greet incoming pests with something a little less like paradise.

To them, that is. All this goes on at the smallest limits of human perception. At scales more in line with our everyday experience, the Haven remains the tranquil sanctuary we have come to expect. There might be an aphid or two in there, but don't worry. I'm hardly working on it.

Andrew Wunschel
Assistant Horticulturist

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Wherefore the fall that makes fall, fall?

Tags: trees, autumn, botany, horticulture, grounds

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Published On 10/25/2012

The last, tremulous notes of the ice cream truck have faded into the distance. Sales of fun-sized candy bars are spiking. And all across this great nation, people are attaching their egos to teams of large, colorfully outfitted men battling over oblong balls. Yes, fall is here, and leaves are raining to the ground like opponents’ home runs onto the bleachers of Wrigley Field. But why? Why would otherwise perfectly reasonable trees decide to shamelessly expose their naked limbs? (In front of the saplings, no less!)

Thanks, guys. You know I'm gonna have to rake that, right?

Well, winter is hard on us all. For plants, the main problem is water, which, like most people, becomes sedentary and expands during cold weather. Sedentary water (by which I mean ice and snow) can’t be absorbed by a plant’s roots. So when the ground is frozen, water lost through its leaves can’t be replaced. Most plants in our area avoid the problem by stripping bare.

As for expansion, water is quite odd in that it becomes less dense when it freezes, so the same amount of water takes up more space when it becomes ice. This is a big deal for plants, since it causes their cells to quite literally explode as the water inside them swells. Try freezing a salad and you’ll know what I mean.

So instead of risking death by dehydration or cell destruction, a clever tree ditches its leaves for the winter. But, you say, ever the contrarian, what about evergreens? Well, your average pine or spruce has small leaves with thick 'skin' to slow water loss. And it's quite industrious, churning out resins and antifreeze compounds to prevent cell damage. Deciduous (leaf-losing) trees can't be bothered to spend as much energy on such nonsense. What antifreeze they do get around to manufaturing is concentrated in their buds in preparation for spring.

All this hard work gives evergreens a competitive advantage in early spring, when temperatures are warm enough for efficient photosynthesis. Deciduous trees can’t get moving until they stop hitting the snooze button and get to work cranking out leaves, while Joe Spruce is already soaking up the vernal sun and adding inches. The tables turn in summer, when the larger leaves of deciduous trees allow them to collect more light and grow faster than our work-a-day friend Mr. Spruce. These differing strategies are one reason evergreens dominate the landscape of northern latitudes. Short summers don’t allow those deciduous layabouts enough time to catch up.

Seth Harper - Museum Horticulturist

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