Science of Life Explorations IPM and the Decision Making Process Decision #2 Lawn Weeds
We re not done with the lawn yet. IPM Steps aren t just for grubs, they work for all pests. What about weeds? Yes, there are weeds. Ask your uncle to find a good source of information to identify the weeds he sees. Once he has identifies the weeds, he should figure out whey they are here. For instance, if he finds ground ivy, it might mean his lawn is not draining well because ground ivy likes wet soil. If he finds plantain, it means his lawn might have compacted soil. Step #1 Proper Identifcation Your uncle identifies two weeds in his lawn, dandelions and plantain. The plantain is along the driveway and the dandelions are all over. Step #2 Learn the pest/host biology Unlike you, grass doesn t grow year round in our climate. But once spring rains and warmer temperatures come along, grass plants do most of their active growing. This growth slows down in warmer weather. Your lawn grasses will be dormant in both very cold weather and during drought conditions.
Plantain can grow in soils that are dry and compact. (Lawn grass does not do well there.) It is often found along driveways and sidewalks. Dandelions grow best in full sun. Each plant grows a long tap root which must be removed or killed to prevent the plant from growing back again. Their seed heads easily disperse in the wind. This is why they are a very common weed pest. Dandelions cause problems in sports turf because each plant grows a tight, bunchy crown which can become a tripping HAZARD. Weeds succeed because they usually can grow well in settings that are not good for grass plants. When soil is compacted, dry and has few nutrients in it, grass can t compete well with weeds. Step #3 Sample the environment for pests. Your uncle found that plantain only grows along his driveway, while the dandelions are spread out across his lawn. The flowers of a dandelion do make a pretty sight despite the fact the plant is generally unwanted. After pollination, the seedhead quickly forms into the familiar puffball. Each seed has its own tiny parachute to ride the wind on. The flowers of the plantain family are much less impressive. The tall, conical flower head has little-to-no color but is skilled at producing seeds. Plantain seeds don t use the wind to move about but instead have a stickiness which helps them travel about on animals and people s feet.
Dandelion photo courtesy of:margaret Williams @ USDA- NRCS PLANTS Database Plantain photo courtesy of James H. Miller. James H. Miller and Karl V. Miller. 2005. Forest plants of the southeast and their wildlife uses. University of Georgia Press., Athens. Courtesy of University of Georgia Press. Image scanned by Forestry Images. Step #4 Determine an Action Threshold Your uncle would like to get rid of these lawn pests before they multiply. He understands that they ve been there for years but now that he has more time, he d like to improve his lawn s appearance. He d like to have a nice, safe place for his young grandchildren to run and play. In this case, your uncle s action threshold is low. You could say that he used to have a high tolerance or threshold for weeds. Now he wants to act to have fewer weeds Step #5 Choose tactics This is an important part of IPM. There are a number of ways we can treat for pests. You may remember that tactics are actions or treatments taken to control or reduce the number of pests. (Tactics can also mean actions you take when you make a decision to do something like study more.) Your uncle consulted some turf professionals and has chosen to use three different tactics.
Here are three tactics you can choose from as you decide your best course of treatment. a) cultural tactics - When talking about plants, CULTURAL means the way you take care of something. In the case of turf weeds, it means taking better care of the lawn and soil and giving it the best chance to be healthy and grow well. Your uncle will use the cultural tactics of: mowing higher watering dry areas adding new grass seed in the spring or fall to help crowd out weeds. b) physical tactics - This means making an actual physical change. For turf, this often means reducing compaction. Compaction means the soil is very dense and hard because it has had a lot of foot traffic or vehicle traffic on it. In your uncle s lawn, plantain was found near the driveway where people walked or drove their cars. You will help your uncle with two tactics. First, remove the weeds and then, help reduce compaction by loosening the soil along the driveway. Your uncle will add some organic matter, mixing it into the existing soil. Later he will plant grass seed and give it a good soaking of water. Your uncle will try to not drive on the lawn any more. c) chemical tactics - Because dandelions have such a long root, they can be difficult to remove completely. Your uncle has removed as many as he could by hand. The local cooperative extension office suggested an herbicide he could use to complete the job. There are many choices when using an herbicide. Some kill all plants and some kill only certain ones. Even with herbicides some weeds can come back. Your uncle will use an herbicide that kills all plants, but he will use it only on the dandelion plant by carefully spraying it only on the weed. This is called spot treatment. Once the plant is dead, he ll remove what he can of the plant. He will start grass seed in those areas.
1. Why should we properly identify a pest before we treat it? attractant - a scent, sound or activity which causes an animal, insect or person to come toward the source colony - the term for the nest or extended family of a group of ants cultural -relating to the way things commonly are, or in IPM, the way a site or area is taken care of hazard - something that may cause damage by chance instar - the periods between molts of larvae livelihood - the way someone provides an income to pay for living expenses preventive - taking steps to stop something before it gets to be a problem sampling - taking deliberate counts or samples of a site or area to find out the population, if any, of a pest sanitation - the efforts to keep something clean to reduce sickness or pests scarab beetle - a family of beetles which includes the Japanese beetle and the chafer scouting - the IPM term for sampling or looking for a pest to determine what it is and how it is affecting the site or area susceptible - being easily affected or influenced by something; often it is due to being in a weakened state threshold - the amount of something that can be tolerated; changes are desired when the threshold is passed turf - a certain kind of grass grown for walking on or playing on; also can mean a top layer of soil containing grass and its roots