By Tami Schlies
Did you know that the mayday tree, Prunus patus, is becoming invasive here in Alaska? Michael Rasy with the UAF Cooperative Extension spoke to us about things to look out for here in the high north that may cause problems down the road. Apparently invasive species can have what is called a “lag period” of up to eighty years before showing signs of becoming invasive. (It makes me a little concerned about bringing in seaberry trees, since they have proven to be invasive elsewhere.)
The mayday tree is affecting stream banks and out competing the native willow, aspen and alder. The native trees are important to the balance that maintain salmon populations in our streams. You will often find mayday seedlings popping up under your bird feeder, so the seeds are spread by birds, and will have far reaching affects.
For those of you fighting leaf rollers every year, Michael suggested using Bt, Bacillus thuringiensis, as a first defense. Leaf rollers munch BEFORE they roll, so you must keep your eyes open for the worms early on. Once they roll up, they are harder, if not impossible, to control.
I have included a publication on Bt, but some fact in a nutshell are: 1.) Bt is most effective early in a caterpillar’s life cycle. 2.) It is a living, biological control, and as such must be replenished every year; don’t use the leftovers on your shelf. 3.) It is not residual; it must be applied weekly for best effect. 4.) It does not harm bees or ladybugs or other beneficial insects. It is a natural bacteria that effects only specific types of larva.
Another worm many of us are familiar with is the currant worm. These are actually the larva of the sawfly, not a moth or butterfly, and they are not susceptible to Bt. You must deal with these nasty critters very early as, well. Michael suggests setting out sticky traps and as soon as you catch a sawfly start spraying with insecticidal soap.
The sawfly looks very much like a common housefly except most of them have a little red spot on the back of them and a little black “cell” on the forewings. The larva also look different from caterpillar larva in that a sawfly larva has six to eight back legs and six front legs with a vacant section in between. Caterpillars have a much bigger vacant section with less rear legs.
The CES office offers free identification of insects and diseases in your garden. Take them a sample and they will do their best to help you figure it out. They want to know about outbreaks so they can develop a plan of action to defend our state against incoming problems. NOTIFY THE CES OFFICE IF YOU FIND ANY FURRY OR SPINY CATERPILLARS OR NOTICE ANY CATERPILLAR TENTS IN YOUR YARD