Tom's Blog

Friday, July 21, 2017

A good year for purple and white prairie clover!

The prairies have benefitted greatly by the extensive rains from mid June-late July. Especially, our dry prairies on the South-facing Slope are lusher than we  have ever seen them. Virtually all prairie species are thriving, but two species that are particularly fine this year are purple and white prairie clover (Dalea purpurea and D. candida ). Even before they bloomed there were large amounts of plants on the south slope (Units 2 and 3). A week ago, white prairie clover was in full bloom, and this week it is purple prairie clover, which, because of its color, is spectacular. You can actually tell these two species apart in the vegetative stage, since D. purpurea leaves are smaller and more delicate.

Both of these species are characteristic of dry prairies, with D. purpurea (C value of 7) being more common than D. candida (C value of 8). Since it is a nitrogen-fixing legume, D. purpurea is often added to seed mixes for CRP plantings, although I doubt whether this delicate species adds significant nitrogen to the soil.

D. purpurea was present at Pleasant Valley Conservancy on the south slope (the “goat prairie”; Unit 1) even before restoration began (1995-97), and we have spread it widely from collected seeds. D. candida was not here and was introduced from seeds collected at two high-quality prairie remnants

 
Purple prairie clover on the South Slope. Lots of other species are thriving on this slope, including compass plant, lead plant, spiderwort, and all the warm-season grasses. Note also the oak grubs.

Purple prairie clover

Wednesday, July 5, 2017

Controlling invasive plants: skills versus strategies

The skills needed to remove invasive plants are deceptively easy to learn. Cutting, pulling, digging, and girdling require little formal training. (That’s why volunteers can be used.) Even spraying is a straightforward activity.

However, the strategies involved are much more difficult. DANGER! If you use the wrong strategy you may be doing more harm than good, or at least may be wasting your time. In my 25 years of restoration work I have watched some strategies completely fail, most of which were applied out of ignorance.

Key strategies: Recognition, identification, timing, choosing the appropriate technique, (mechanical or chemical?), team organization. Knowledge and judgement are key.

Developing strategies: Start with knowledge of the bad actors, read the scientific literature, government manuals (but don’t assume they are infallible). Use the Internet judiciously. Especially avoid undocumented suggestions from others. (Lots of misinformation is passed around.)

Learn the important plant characteristics: monocot or dicot; Latin name; life cycle; clonality; habitat; phenology; annual, biennial, or perennial; herbaceous or woody.

Important items: Early detection monitoring, location maps, risk assessment (triage, see below), measurement (size of population; scattered, patchy, massive), identification, timing (season), choosing the appropriate technique, (mechanical or chemical; often combined).

Understand herbicide chemistry, biochemistry, fate in soil or environment. Read the label. Experiment! Mark your experiments with flags or stakes. With rare exceptions, you can’t eradicate invasive plants without at least some use of herbicides.

Nothing can replace extensive field experience! Get out there and take notes

Risk assessment (triage). Place the target into one of these 5 categories
1.     Eradicate everywhere
2.     Eradicate in high-quality areas
3.     Control spread
4.     Control if time available
5.     Ignore [can’t stand competition?]

Early detection is important

Set up a thorough survey method; AT DIFFERENT SEASONS OF THE YEAR!!

Use of a plant’s characteristics to help detect it: fall color; flowering (especially important); early appearance; size; habitat (prairie, savanna, woodland, wetland); legacy effects (history of the site).

Keep coming back to sites already restored, because it is almost certain there will be more plants to deal with, either plants missed or new growth. Don’t assume the site is clean! Unfortunate but true.

Don’t let the word “native” seduce you. Among others, sandbar willow, Canada goldenrod, and smooth sumac are native, but are generally “malignant” under present conditions.

For successful invasive plant control, a strong work ethic is needed. Get it done!

Don’t let these things happen:
·       You pulled the wrong thing.
·       You sprayed the wrong thing.
·       You worked at the wrong time.
·       You worked at the wrong site.

If you are using contractors, monitor them closely. Until they have a “track record”, it is best to have a manager on the site while a contractor is working.