IPM Fun with Insects, Weeds and the Environment. Lesson #3 Weed IPM. The New York State Integrated Pest Management Program

Transcription

1 IPM Fun with Insects, Weeds and the Environment Lesson #3 Weed IPM The New York State Integrated Pest Management Program Learn how you can use the 6 steps of integrated pest management to help protect the environment.

2 Insects aren t the only pest. The battle against weeds in our lawns, gardens and fields goes on and on. What makes a plant a weed? That question requires some thought. Plants evolve in an ecosystem and perform specific roles. When we till the soil to grow crops or plant landscapes, unwanted plants will show up because seeds are everywhere. Sometimes, when plants are brought in from other places, they out-compete local plants and become invasive. Plants that we put into landscapes are often the same plants we find in wild places. They are often changed (bred) to make bigger flowers or bloom longer, but they are still related. Weeds are basically plants that grow where we don t want them. Plants reproduce in different ways, but most make seeds. This illustration shows flower parts that produce pollen. Pollination creates seeds. 2 We generally call every plant that is not purposely planted in our landscape or garden a weed. Plants are meant to reproduce and seeds will manage to find a way into even the most welltended gardens. They will germinate in even a small amount of soil, if there is moisture and warmth present. However, without moisture and sunlight and enough soil to support it, the new plant will not survive.

3 Is a corn plant a weed? What if a corn plant grew in your mother s rose garden? Weed plants are not just annoying, sometimes, they cause problems. Weeds compete for water and nutrients with the plants we WANT to grow. What do plants need to grow? Can you think of two things that plants need? sun. water They use these two things, along with the nutrients in soil to grow and survive. Sometimes weeds are bullies and the plants we want to grow do not get what they need. Some weeds can also be harmful, such as ragweed that cause allergies, and poison ivy that causes a painful rash. How can weeds be beneficial (helpful)? Weeds hold soil in place and prevent erosion Weeds are food for wildlife and humans Weeds create habitat (cover) for wildlife Weeds beautify the landscape. A meadow is very pretty, but all those plants could be called weeds, couldn t they? Weeds are used in some medicines Who decides what plant is a weed? What do you think about weeds now? You do. We all do. When we like a plant and it s not causing trouble, we don t really want to get rid of it. When a plant is in the wrong place or causing a problem, we call it a weed. Everyone may have a different opinion! 3

4 Where do weeds grow? Everywhere! Lawns, gardens, in sidewalk cracks, fields and ponds. Weeds are pretty hardy plants. They can survive in some poor conditions and will adapt, often doing better than the plants we want to grow. That is why there are so many! Weeds tend to take over in turf areas where the soil is compacted by vehicle or foot traffic. Can you see how clover has grown into this ball field base line? Why do they keep coming back? Weeds, like many plants, create a lot of seeds. Seeds can stay in the soil for a long time and not germinate. But when the conditions are right, they will start a new plant! Some plants reproduce by spreading along the ground or underground. Plant parts such as bulbs, stolons (above ground stems) and rhizomes (below ground stems) can start a new plant next to the older plant. These plant parts have stored energy, so they can easily start over. How do plants get around? When you move soil, you are moving seeds and pieces of plants. Seeds can spread by: wind, water, animals and birds eating them, sticking to animal fur, and movement of soil or mulch

5 Why is it important to be able to identify weeds? You need to know if it is a plant you want or not. It also helps you decide how to deal with it. When is the best time to identify a weed? Why? After a young plant has a few sets of leaves, it is easy to use a key and identify the plant. Good plant photos of young plants are very helpful. If you identify weeds when they are young, they are easier to remove and haven t had time to spread seeds! 5 Time to get out for a walk. Encourage students to look at the plants in the lawn and in borders. The next pages encourage students to examine the weeds they find and describe them. If you have access to a digital camera, you might be able to photograph their selections and examine them on the computer screen again. Hopefully you have found some weed or wildflower ID books in your school, or local library. Your adult volunteers are a good resource also.

6 Be a plant detective! Notice the features of a plant and learn to identify it. How is it growing? Is it upright, or crawling along the ground? What kind of leaves does it have? What shape are they? Are they large or small? Are they in groups? What kind of flowers does it have? What is the shape, color and size of the flower? Where is it growing? Does it seem to prefer dry soil, moist soil, shade or sun? When you have looked closely at the plant, look around at the site. Is the plant in a place where it is likely to cause a problem? How have the conditions affected the plant? How can we prevent weeds from causing problems? Understand your site conditions and choose plants that can compete with weeds. Don t bring seeds in by mistake in soil or mulch. Remove weeds when they are small. Sometimes we can reduce the number of weeds by: Placing mulch over bare soil (seeds don t get sunlight to germinate) By removing them (hand or mechanical weeding) By mowing them repeatedly (this causes stress and eventually they won t have the strength to grow). *Mulch is usually organic matter like shredded bark, leaves, or wood. Water and air must be able to pass through it but not sunlight. Mulch should be not be more than a few inches thick and should not be placed against the trunks of trees and shrubs.

7 Weed Hunt The best way to learn how to identify plants is to examine them closely. Look at five different weeds in your lawn or field. Look at the shape of the leaves and the growth pattern (does it grow up and get tall or grow low along the ground?) What are the stems like? Are the leaves fuzzy or smooth? If it has flowers, what color are they and what is their shape? Use one of the resources and the chart below to identify five plants. Weed Name How did you verify the name? Helpful Identifying Feature #1 used a plant key checked a reference asked an expert #2 used a plant key checked a reference asked an expert #3 used a plant key checked a reference asked an expert #4 used a plant key checked a reference asked an expert #5 used a plant key checked a reference asked an expert What are some of the differences you found in the plants? After students have had a chance to look for weeds, have them discuss their experience as a group. You might list the different weeds on the board and count the number of samples found. This information can be used to create a chart. 7

8 Here are photos of common lawn weeds. Can you find them in your lawn? clover bedstraw ground ivy narrow leaf plantain speedwell or veronica

9 oxalis broad leaf plantain dandelion wild strawberry

10 Here are three tactics used to reduce the number of weed pests in turfgrass. Cultural tactics: When talking about plants, CULTURAL means the way we grow and take care of plants. In the case of turfgrass weeds, it means taking better care of the lawn (turf) and soil. This gives grass the best chance to be healthy, and healthy turf has fewer weeds. Cultural tactics for turf include: mowing the grass at about 3 tall watering dry areas adding new grass seed in the spring or fall to help crowd out weeds fertilizing correctly in the fall Physical tactics: This means making an actual physical change. For turf, an example is reducing compaction. Compaction means something has been pressed down or pushed together. Compacted soil is very dense and hard and often dry and it is hard for plants to grow there. Soil compacts in heavily used areas of sports fields, under playground swings, where people walk and many places where cars drive on the turf. Look for areas where people step off the sidewalk and walk on the lawn. Do you see a difference in the grass? Are there a lot more weeds? What does that show you? Compacted soil should be loosened. This can be done by aerating a sports field or rototilling an area and replanting it. Try to stop people from driving where you are trying to grow grass. Chemical tactics: Sometimes it is really difficult to get rid of turfgrass weeds. For example, the dandelion has a very long tap root. It is hard to remove by hand. If the plant breaks off, the root will grow a new plant. Sometimes an adult might decide to use a pesticide. Pesticides that kill plants are called herbicides. There are many choices when using an herbicide. Some kill all plants and some kill only certain plants. If an herbicide must be used, a good way to remove turfgrass weeds is to just put the herbicide directly on the weeds, instead of spraying the whole lawn. This is called spot treatment and reduces the amount of pesticides used. 10 The 5th step of IPM is Choose Management Tactics This page gives three tactics for reducing weed pests. Think of tactics as treatments or actions.

11 Review your knowledge of weeds: Weeds compete for water, sun and nutrients, so they are not wanted in our lawns, gardens or crop fields. What do you think is the difference between a weed and other plants? A weed is a plant that is out of place or unwanted because it is competing for sun, water, soil and nutrition from desired plants. It might create a lot of seeds, or spread rapidly. Many plants that we call weeds are really not causing problems when they are not out of place. Plants have important functions in our ecosystems. What are two things that weeds do that are helpful? 1. Weeds often help hold the soil and prevent erosion Weeds provide habitat for helpful insects. 2. Weeds spread in many ways. They generally create a lot of seeds which can be moved around by wind/ water and. animals/ birds/ people The best time to identify a plant and remove it before it causes problems is to a seedling/ small/ young examine it when it is. Name one or more resources you can use to help identify a weed: a plant guide, an identification key, a professional 11