Many people believe that rain would wash our products away and render them ineffective, but this is just not true. Actually, rain improves the effectiveness of our lawn treatments. Once integrated into the soil, the pre-emergent will prevent weeds like crabgrass from sprouting in your lawn. During dry periods, the herbs' oils will still be active and will continue to protect your yard.
The pre-emergent contains chemicals that stop seeds before they can grow into plants. These seeds include pollen and embryo cells from last year's grasses. When these seeds come into contact with these chemicals, they are killed off so they cannot grow into new plants. The pre-emergent also contains chemicals that destroy existing grasses seeds and seedlings. This kills off any young shoots that might otherwise grow into new plants.
Weeds are the enemy of every homeowner who wants a neat, clean yard. Without weed control, yards become overrun with plants that don't belong there, causing aesthetic problems as well as health hazards for people who may not realize the weeds contain toxic chemicals. Herbicides are available in liquid, foam, or dust form. They should never be applied to lawns that you plan to play in because the chemicals will not break down fast enough and will remain in the environment long after you think it's safe to go back outside.
Before it rains, the optimum time to apply crabgrass preventer is before it rains. The preventer will have been washed into the soil and crabgrass seeds after raining, preventing them from growing roots and sprouting. If you apply after rain, quickly water your grass to wash the pre-emergent into the soil. This will protect your lawn from developing seeds that would otherwise grow into crabgrass plants.
The best way to control crabgrass is to use a pre-emergent herbicide. These chemicals kill both the existing weeds as well as any young shoots that may have developed since they were last treated. They work by slowing down the growth of plants like grass and other weeds so they can be killed by shallow watering or by spraying with a tractor. Use caution not to spray these chemicals in areas where you want your grass to grow, such as around trees or buildings.
If you have an infested area of lawn and want to try to control the crabgrass without using a pre-emergent herbicide, try pulling up each plant by its root ball when it's wet. This will destroy the underground stems that hold the crabgrass plant together and cause it to die. Don't do this until just before it rains so the chemical will be able to penetrate the dead tissue of the plant and kill any remaining seeds.
Finally, if you see young crabgrass shoots coming through the soil, remove them by cutting them off at the ground level.
Pre-emergence herbicides applied to the soil at the start of the growing season require rain or irrigation to be activated. This water converts the pesticide into a solution that weeds may absorb. Too much rain, on the other hand, can dilute the herbicide and cause it to leach or wash away. The best time to apply herbicides is when the soil is dry but not bone dry. Damp soil allows for better absorption of the chemical.
Herbicides are classified as either broad-spectrum or selective. Broad-spectrum herbicides kill almost all plants, while selective herbicides kill only weedy plants. This article focuses on selective herbicides.
Selective herbicides are used to control weeds that are harmful in urban environments or where alternative crops are used for cover. They can also be used before planting a new crop to prevent seeds from spreading. Examples of selective herbicides include Alamo (imazethapyr), Aim (acetochlor), Altacor (mecarbam), Bluestar (2,4-D), Champion (trichlorfon), Confident (benthiocarb), Conquest (pyraflufen-ethyl), Encore (encainite), Force (fluoroacetate), Harness (zinc).
Some selective herbicides are toxic to humans.