As you are trying to adjust to a shift in daylight it doesn’t hurt to think about rosettes also. I am not talking about County Fair. I am talking about weeds. The weed rosette is the first layer of leaves that establishes above ground each growing season. Depending on the specific life cycle of your choice target weed, this is often the best time to control weeds.
As all plants start to grow each year they pull carbohydrate energy reserves from their roots and seed coatings to establish and grow a plant. Just when their leaves first establish they are still pulling more nutrients from reserves than their initial leaves can generate via photosynthesis. Once their leaves are well established and larger in number they can focus on generating more leaves, generating seeds, and pumping carbohydrate reserves back into the ground for the next growth period. It is a balance issue in that if their leaf factory or root reserves are interrupted the plant struggles. This happens for all plants including those you find desirable and the ones you consider weeds. When to most effectively impact weeds depends on their physiology and their life cycle.
There are three basic life cycles in plants including perennials, biennials and annuals. Perennials are long-lived and grow from root stock reserves each year. They may reproduce via seed, vegetative growth or both. But they are there in the soil every year so it’s important not to let them get started or well-established in the first place. With perennials you can impact the plant by addressing rosettes in the spring and when they emerge again. To really impact them you must do that and treat them in the fall just as they are trying to go dormant so they pull the impacts and the herbicide down into the roots. Over the winter the roots will struggle and the next spring the “stand” of plants will be lessened. Repeating the process will eventually address the infestation. Some plant species have stolon (above ground runners) or rhizomes (underground runners). If your target has either of these you need to think about the community of plants. All of the connected plants must be controlled to be effective. We always suggest using Integrated Pest Management to address weeds which can include a combination of cultural, chemical and biological controls. In the case of rhizomes and some stolon, chopping them up with a shovel or rototiller simply creates a new crop of separate plants. Remember to weaken them with other controls before disturbing runners.
Biennials have a two year life cycle (usually) where they form a rosette and heavy roots the first year. The following year the root grows a seed stalk and releases the seed to start the cycle over again. By aggressively attacking the rosette you can put a halt to the entire cycle. The other method is to cover, clip off or graze the seed pods (flowers) when they are immature and prevent them from spreading the plants. Unfortunately even if you stop reproduction by controlling seed spread you still have to deal with the standing stalks as debris. The rosette control leaves less to deal with.
Annuals are plants that grow from seed each year, develop a seed and then the cycle starts over again. These plants have very minimal root reserves of carbohydrates and energy which allows you to pretty much control an infestation by killing the rosettes before the plants grow up. Remember, even if dealing with annuals you may have a significant seed stock in your area that requires several years of work.
Rosettes are just leaves on the ground and since they have no flowers they are harder to identify. You can always go online with a photo or take a good photo to send to your local UW Extension or Weed & Pest District to get help with identification. Actually carrying the plant to us may spread seeds as you go which is undesirable. I suggest taking a close up of the rosette and a landscape view so we can see the surroundings. The photos need to be very clear – identification is all about details.
Last but not least understand that desirable plants such as gardens, flowerbeds, trees and pasture need to be treated just the opposite so that they get every opportunity for low impacts and maximum energy reserves. Protect their leaves and growth as much as possible. The desirable rosettes are champions like our 4-H youth, the undesirable rosettes are losers.