Weed Control in Home Gardens is part 8 of The Alabama Vegetable Gardener series.
Good weed control may determine to a large extent the success of your home garden. Weeds compete with the crop for soil moisture, sunlight, space, and plant nutrients. They compound disease problems and serve as hiding places for insects. Also, weeds may prevent dusts and sprays from thoroughly covering your garden plants, resulting in poor pest control.
Weeds can usually be divided into two groups—grasses and broadleaf weeds. Grasses are multistemmed plants with fibrous root systems. Once grasses become established, they are difficult to control without injuring the vegetable crops. Grasses are very competitive in gardens and make harvesting difficult. Many broadleaf weeds grow upright and have taproot systems that make them easier to pull than grasses; therefore, the vegetables receive less injury.
New weed seed may be brought into a garden on plows and mowers that have been used in weedy areas. Poultry litter, compost, and manures sometimes contain troublesome weed seed. Weedy hay used for mulch may bring a number of new weed problems. Occasionally, home-saved vegetable seed may also include some weed seed.
Most of the weed problems in the garden are homegrown problems. That is, they come from weed seed produced in the garden in years past. Season-long weed control to prevent weeds from reseeding should be a basic part of any weed control program. Controlling weeds by preventing them from making a seed crop may be a long-term process, but in the end it is the only sure way to control this problem.
Historically, gardeners have used hoeing, plowing, hand-pulling, and mulching to control weeds. Mechanical control methods used on a regular and continuing basis provide good weed control for serious gardeners. This usually means frequent, shallow cultivations with a plow and hoe to destroy weeds in the two- to four-leaf stage. A few minutes spent destroying the flush of weeds that usually emerge after every rain is much more effective than hours or days spent trying to destroy established weeds.
Many gardeners have too large a garden to control weeds in the time available for that task. A few well-managed rows may produce greater yields of higher quality vegetables than a larger area tended in a slipshod manner.
Mechanical weed control gives immediate results. There are no problems of uniform application, drift, and residues as with chemicals. Weeds may be controlled mechanically under a wide range of soil moisture conditions, and very little skill is required. Also, mechanical methods may be used as often as needed. Mechanical weed control is the most practical approach to weed control in small gardens. The greatest weakness of mechanical methods is the lack of residual control.
Mulch can be a valuable asset in controlling weeds in perennial and long-season crops such as asparagus, strawberries, tomatoes, and peppers. Six to eight inches of pine straw, leaves, or well-decomposed sawdust will help suppress most weed problems. Mulch helps keep the soil surface cool and cuts down the evaporation of soil moisture. Many gardeners clean-cultivate early and mulch heavily to control weeds in long season crops such as tomatoes, peppers, and okra, because late cultivation could damage these large, spreading plants.
Mulch gradually decomposes during the season, and sometimes this may cause plants to develop a slightly yellow cast. A light application of about 1 pint of 33-0-0 per 100 feet of row will usually correct this problem. Additional mulch may be added as needed when the older material settles or decomposes. At the end of the season, the mulch may be turned under or incorporated to add organic matter to the soil.
Most annual grasses are easily controlled with garden-approved herbicides. However, herbicides only control small-seeded, annual broadleaf weeds that grow from the upper 1 to 2 inches of soil; they usually do not give acceptable control of large-seeded broadleaf weeds.
You can use a herbicide for grass control and then rely on hoeing, plowing, hand-pulling, and mulching to control weeds that escape the chemical treatment. It is not advisable to use a herbicide unless you are also going to control broadleaf weeds. Removing just the grasses would only remove some of the competition and would allow the broadleaf weeds to flourish. In a very short time, these weeds would replace the grasses and create an almost hopeless situation.
Chemical weed control will be improved by preparing the seedbed well. Destroy old crop residue and turn it under early enough for it to decompose. Spread manure and apply lime and fertilizer as recommended by soil test. A uniform, well-prepared seedbed will result in a quick crop stand and improved weed control.
Chemicals used where transplants are to be set should be timed as directed on the label and applied to a weed-free seedbed. Weeds germinating before transplants become established should be removed before applying herbicides.
Methods of Application
Read the label instructions before attempting to apply any chemicals. Cyclone seeders or spinner-type applicators are best for applying granular herbicides. Granules sold in shaker cans should be applied in two light applications going in different directions to get uniform application. Add liquid formulations to about one-half the required water before adding it to the sprayer tank. Make wettable powder herbicide formulations in a slurry in a bucket and strain the slurry as you add it to the sprayer tank.
Some herbicides may leave residues that could injure certain susceptible second crops. Avoid this by either selecting a tolerant second crop or by using a herbicide that does not leave a harmful residue.
Estimating or pacing off areas to be treated with a herbicide may lead to serious errors in application rates. You need a 50- to 100-foot tape to get accurate measurements. Use flags or stake markers to identify the area measured for treatment.
The bucket or sack-type cyclone seeders and spinner-type lawn fertilizer spreaders are very satisfactory for applying granular herbicides. Many models have a calibration sheet that can be used to calibrate the spreader for applying herbicide granules.
Pressure sprayers in 1-, 2-, and 3-gallon sizes are usually used to apply liquid and wettable powder herbicides. The 2-gallon size is the most popular except for growers with very large gardens. These are available in stainless steel and galvanized metal tanks. The galvanized models cost less but have a relatively short life before rusting out. The more expensive stainless steel models should last indefinitely.
Use a tape measure to determine the number of square feet to be sprayed. Consult the label for the rate of application. Accurate measurements, correct weights, and uniform application are essential for good weed control without injury to the vegetables.
Apply liquid concentrate and wettable powder herbicides in about 2 gallons of water per 1,000 square feet with a compressed air sprayer. Application errors are not a serious problem when sprayed at this dilution rate; however, they often become much more serious as the chemical concentration is increased. For this reason, it is not advisable to reduce the water rate. If the water rate must be adjusted, it would be better to increase it and spray the area twice going in different directions.
Liquid or wettable powders must be agitated to prevent settling to the bottom. Periodically shake the sprayer tank while spraying.
Do not use a sprayer that has previously been used for applying 2,4-D or similar type herbicide. Immediately after use, take the nozzle apart and clean the strainer, back flush the boom and hose, and thoroughly clean the tank before storing the sprayer.
Because of the high variability among vegetable crops, weed problems, cultural practices, and soil types, no step-by-step standard weed control system has been devised. Using a combination of mechanical weed control and mulching herbicide treatment—capitalizing on the best features of each of these practices—is the best approach to weed control in the home garden.
Always follow the manufacturer’s directions printed on the label for handling and use of herbicides. Proper storage and safe disposal of empty containers are important.
Read the complete Alabama Vegetable Gardener.
- Part 1—Planning for the Home Garden
- Part 2—A Well-Drained Soil
- Part 3—Acid Soils Create Gardening Problems
- Part 4—Excessive Phosphorus in Garden Soils
- Part 5—Wood Ash for Lime and Potash
- Part 6—Garden Fertilizer
- Part 7—Fertilizing the Organic Garden
- Part 8—Weed Control in the Home Garden
- Part 9—Growing Tomatoes
- Part 10—Bitter Cucumbers
- Part 11—Home-Grown Seed
- Part 12—Vegetable Information
- Part 13—Control Diseases for Top-Quality Tomatoes
- Part 14—Nematodes Could Be the Reason Garden is Unproductive
- Part 15-Vegetable Garden Insects
- Part 16-Garden Problem Guide
- Part 17-Harvesting Your Own Groceries