Weeds, Pests & Diseases Notes

Why?

Weeds, Pests & Diseases can affect the beauty, health and vigor of plants. They can also decrease yield in fruit and vegetable crops. They can prevent growth, development or flowering of plants as well.

Good management analogy: If you have a dog that you feed outside, and you expect the dog to be the only creature to eat that food you are crazy. Cats, deer, raccoons and any number of other animals will most likely eat that food. You can’t expect to only feed the dog. The same can be said for the plant world. Weeds need many of the same things that desirable plants require. If you give the desirable plants what the weeds need, you will aid weed growth alongside the plants you want to have there. On the other hand, if you learn what the desirable plants need to make them the healthiest, many times you can crowd out or otherwise kill the weeds and weed seeds.

A healthy plant is a lot more susceptible to disease and pest damage than one that is under stress. Healthy plants are more able to outcompete weeds in the garden as well.
Also, choosing appropriate plant varieties can limit the amount of pest and other damage.

I am not going to talk a lot about specifics. There are too many to cover. So, if you have a specific problem, ask.

WEEDS:

Good Chemical Control of Field Bindweed : (80-95%) Selective Lawn Herbicides
2,4-D+MCPP+dicamba (Trimec, Weed-Out, Weed-B-Gone, etc)
2,4-D+dicamba+MCPP+MSMA (Quadmec)

Annual weeds: Generally, pull annual weeds. Or spray them

Perennial weeds: You have to make sure to kill the whole plant, not just the above ground part. Many have rhizominous roots that will create new plants from each piece left in the ground.

Approaches:

Biological–Use of beneficial insects to reduce amounts of weeds.
Cultural–Maintaining healthy plants can prevent weeds from invading. Also, use of specific varieties can aid in competing with weeds.
Herbicide–Read all labels and follow precisely–to do otherwise is breaking federal laws!!
Mechanical/Physical–Pulling and tilling are methods to kill weeds that don’t have roots that can reproduce from pieces.
Prevention–First line of defense. If you can keep it out in the first place, you don’t have to deal with the detrimental effects later.

Identification: Call extension specialists or look online or in a book. When you know what you are dealing with and what its life-cycle is, you can know better how to manage it.


Biological wildfire:

Wild fires and weeds have many things in common: Impacts, Spread & Management

Management: Prevention, Detection, Suppression (Control) & Revegetation


Noxious Weeds:

The Utah Commissioner of Agriculture decides which weeds are noxious. To be considered noxious a weed must be non-native, invasive and poses a serious threat to native plants, wildlife habitat, crops or livestock.

Land owners are responsible for the control of the official noxious weeds growing on their land.

There are also county noxious weed. Counties are asked to keep these to a minimum to reduce confusion.

Weeds in a lawn: (from USU extension publication HB 508 April 1997)

First, maintain a healthy lawn and you will have less problems. If the lawn is thick and deep, it can out compete most weed invasions.

Buy weed-free seed! The label on the seed is required to list the amount of weed seed included. If you buy cheaper seed, you may be getting more weed seeds than if you paid more for the seed in the first place. Then, you can spend more of your time and money on other parts of your landscape, rather than on the weeds that you planted with the grass seed.

Fertilize properly so that the grass can be thick and healthy. If it is very healthy, it can out compete the weeds.

Mow at about 2 ½ inches and keep the blades sharp. Mowing too low can cause damage and allows for weeds to come in.

Irrigate properly for your soil. The more clay that is in your soil, the less frequently you will need to water. Also, allow the top ½ inch of soil to dry out between waterings so that weed seeds are killed.

General Weed Control Rules:

Don’t let weeds go to seed
Kill weeds when they are young
Good management will keep out most weeds
One year’s seeding equals seven year’s weeding
Pesticides are safe if used properly and according to the labels–just because a little herbicide is good doesn’t mean a lot is better.

INSECTS:

IPM–Integrated Pest Management (from USU extension publication AG/IPM/01 April 1996)

Holistic, ecologically based, can be used anywhere
IPM utilizes multiple techniques (cultural, biological, chemical, mechanical)
Emphasizes reaching tolerable levels of insects not complete eradication
Incorporates economic sustainability
Takes into account environmental and social concerns

Strategies:

1. Do nothing–You decide that the levels of insects is below the point that you do anything, so you don’t.
2. Reduce numbers–use cultural, chemical or other means to reduce the number of insects.
3. Reduce susceptibility of crop/ecosystem–rely on changes made to the plant to improve resistence to the insect
4. Combine strategies

Key Steps:

Know your plant and pest
Decide what is unacceptable pest damage (economic injury level)
Consider all pest management options
Time pest controls with pest vulnerability

Non-native weeds and insects can be a problem because they don’t have the same ecosystem to keep them in check that they had where they are from. Use of biological control can be effective when organisms from those countries of origin are used.

DISEASES:

Choose plant varieties that are resistant to disease. Create an environment that is not conducive to the growth of disease. When you do get a diseased plant, find out what the disease is and how to get rid of it. In general, remove diseased plant parts and plants and sanitize any tools that have come in contact with the disease.