Monday, September 18, 2017

Eliminating Invasive Plants – Summer Activities

As the seasons change, my management activities change.  Summer is a time to hunt and eliminate invasive forbs and grasses.  Sweet Clover was my initial target several years ago.  As Sweet Clover numbers dropped, I added other species that could be controlled by pulling prior to setting seed.  Now, Yellow and White Sweet Clover, Wild Carrot, Teasel, and Oxeye Daisy are all on my summer pulling schedule.  Not all invasive species can be controlled by pulling.  Sometimes, like in the case of Crown Vetch, the aid of a chemical herbicide is necessary to eliminate the plant.

This is my second year using the chemical Clopyralid in the treatment of Crown Vetch.  Clopyralid kills only broadleaf plants, and is particularly effective on legumes.  Grass is left unharmed, so no bare spots are left in the field after treatment.  The areas I treated this year were fewer in number and much smaller than what I dealt with last year.  Shown above is the largest patch of Crown Vetch I had to spray this year, and it covered only about 40 square feet.

Crown Vetch found its way into my fields as seed that was produced along the edges our township road.  I eliminated the roadside vetch last year, but some of the affected field areas are going to take a bit more work.  Crown Vetch growing beneath the canopy of tall Indian Grass is hard to spot.  The best time to search is when the plants begin to flower.

Unfortunately, peak flowering time for Crown Vetch coincides with flowering of other lavender bloomed plants such as Monarda.  Shown above is Crown Vetch on the left and Monarda on the right.  Colors are almost identical.

Monarda flowers are held above the Indian Grass leaves.  Good luck trying to spot a couple stalks of Crown Vetch hidden down in the grass.

Johnson Grass is another species that requires some herbicide assistance if it is to be eliminated.  I’ve been after this species for several years and only found seven small clumps growing this year.

When dealing with Johnson Grass, I first cut the stalks down to a manageable height and trim back any long, flowing leaves.  This allows me to spray the complete plant with glyphosate, without spraying a lot of neighboring plants.

Johnson Grass is another invasive species that can trace its origin back to the roadside.  Even though the roadside along my property is free of this invasive grass, seed produced along other sections of the road are easily caught and transported by vehicles traveling the roadway.  I expect passersby will replenish my seed supply on an annual basis.

Johnson Grass is hard to miss when it sends up a flower stalk.  This species puts on height in late July, long before the tall prairie grasses, so it doesn’t take much searching to identify new infestations.

When the plant is blooming, tops can be cut and just left in the field.  There is no chance that these flowers will produce viable seed if removed from the plant at this stage.  If treatment is done after seed has formed, it is best to remove the seed heads from the field to eliminate any viable seed being left behind.

I began pulling Wild Carrot six years ago.  I’ve had a lot of success in reducing the numbers of this plant.

Areas that once yielded hundreds of plants, are now producing only a few plants each year.

With fewer plants to pull, I can cover more area.  This is the last of the Wild Carrot infested barrens, an area that I have never had time to get to before.  I was able to finish off this field just as the pulling season came to a close.

Wild Carrot seeds were just beginning to darken during my last week of pulling.  Not knowing if these seeds were developed enough to finish ripening on a pulled plant, I removed the seed heads and bagged them for disposal somewhere other than the middle of my field.

A single Black Swallowtail caterpillar was found on one of the pulled carrots.  I transplanted it to a domesticated carrot variety in my vegetable garden.  It ate for several days and then disappeared.  I hope it went off to find a secure place to pupate. 




Friday, September 15, 2017

Cycnia inopinatus Caterpillars

I’m always pleased when an uncommon plant or animal species shows up in unusually large numbers. This year, I am finding the caterpillars of the Unexpected Tiger Moth, Cycnia inopinatus, to be several times more abundant than they have ever been in any past year. Having a bright orange body decorated with tufts of black hairs, this species is hard to miss when it’s around.

The Unexpected Tiger moth is listed as an endangered species in the state of Ohio. Its caterpillars feed exclusively on milkweeds, with Butterflyweed, Asclepias tuberosa, probably being the most common host plant. So far this year, I’ve found caterpillars on Butterflyweeds scattered over about a 30 acre area.

In late spring and early summer I’ve seen the caterpillars feeding on Spider Milkweed, Asclepias viridis. Recently, I’ve found several caterpillars feeding on the leaves of Common Milkweed, Asclepias syriaca.

A five-year-old clump of Butterflyweed growing next to my driveway is currently hosting a half dozen caterpillars. Later this year the caterpillars will move into the leaf litter at the base of the plant and pupate. They will remain there through the winter and emerge as adults next spring.

The Common Milkweed being used as a host plant is growing at the edge of my water garden. So far, this is the only Common Milkweed plant that I have found hosting any Unexpected Tiger Moth caterpillars.

Oleander Aphids have been abundant on all of the milkweeds this year. Caterpillars seem to avoid leaves that are excessively covered with aphids and honeydew, but there are enough clean leaves that the caterpillars do not seem to be lacking an adequate food supply. I hope this abundance of caterpillars results in record numbers of adult moths next spring.

video

The above video shows some of the typical caterpillar activities.

Wednesday, September 13, 2017

Immature Cooper's Hawk

An immature Cooper’s Hawk has been hanging around beside the house for the past week.  Its usual perch is atop the stump of a limb rising from the body of a downed Silver Maple.  This puts the hawk in plain sight about 5 feet above the ground and 15 feet from my bird feeder.

Intermittent showers from the remnants of hurricane Irma have kept the young hawk looking rather bedraggled the last two days.

The hawk is vigilant about checking out any animal movement nearby.  A pair of Cooper’s Hawks has been hunting around the bird feeder for years.  It’s possible that this bird first visited here with its parents.

This may seem like the best place to sit and wait for a meal to come by, but it doesn’t work at all.

video
The above is a short video highlighting some of the hawk’s behavior.  Mostly looking and preening, with a nice tail fan in the last half.  The video was filmed from inside the house, so there are no interesting nature sounds to be heard.