- Here is Dr. Gallandt's article: WEED MANAGEMENT for SUSTAINABLE AG SYSTEMS: A TWO-PRONGED APPROACH to SEASON-LONG WEED CONTROL »
- And here is where you can read the updated information previously published here, on TARGETING ANNUAL & PERENNIAL WEEDS »
Scouting for pests and diseases
One of the fringe benefits of weeding is that while you are out there hoeing or hand pulling weeds, you can monitor crops for any signs of damage from pests or diseases. Turn over leaves and look at the undersides, as that is where many insects lay eggs and where diseases first appear. If a plant is wilted, pull it up and look at the roots to see if they are stunted or rotting. Unless you are familiar with a specific insect and know that it's going to harm your crop, do some research before you take action.
Many insects are beneficial and you should learn what they look like in all their life stages so you don't inadvertently kill these allies. Likewise, learn the life cycles of pests that are common in your area so you can watch for them even before they start to do damage. We highly recommend the book Garden Insects of North America by Whitney Cranshaw. This is a huge (656 pages), comprehensive book about insects that are likely to be found in vegetable and fruit fields and gardens. Insects are categorized by the type of damage they do, which makes it easy to narrow down the potential culprits when you spot a problem.
Another essential reference is Identifying Diseases of Vegetables from Penn State University, which includes concise descriptions and large color photos of common diseases.
In addition, there are many online resources to help you identify problems. Check with your State Extension Service to see if it has an IPM (Integrated Pest Management) program for vegetables and fruits. If so, you might find information that will be targeted to your area. If not, do an internet search for "IPM vegetable" and pick the site from the state nearest yours. Many of these IPM sites have excellent photos.
Once you know the nature of the problem you're dealing with, you can turn to Johnny's chart of physical, biological, and botanical controls for all the most common pests and diseases of vegetables.
The chart lists multiple strategies, from row cover to inexpensive repellents to certified-organic insecticides.
Keep records of pest and disease outbreaks. Write down the dates you noticed the problem and took action on it; the plant's stage of development; the temperature and general weather conditions. Review your notes at the start of next season, and you'll be better prepared to catch problems before they become serious.
First, please note that this information applies only to indeterminate tomato varieties. Determinates should NOT be pruned because pruning will reduce yield.
Indeterminates, however, will grow until killed by frost, always dividing their energy between vegetative growth and fruit production. Appropriate pruning reduces vegetative growth to the minimum required for plant health, thereby increasing the energy available for flowering and fruiting. Pruned tomatoes produce larger fruits that ripen earlier, sometimes by as much as two weeks. Pruning also helps prevent foliar diseases because it reduces crowding and touching of leaves. Too much pruning, however, can result in fruits with sunburn, catfacing, and blossom end rot.
Indeterminate tomatoes are vining plants with many branches. Pruning reduces the number of branches to one, two, or several main branches or "leaders" which will ideally be about the same size. This is accomplished by removing side shoots or "suckers" that grow in the leaf axils between leaves and the stem. Here's how it's done:
1. If you want just one leader, remove all the leaves and side shoots below the first flower cluster. As the plant grows, continue to remove all suckers from the leaf axils.
2. If you want two leaders, which is often recommended in case the main stem is damaged, leave one sucker directly below the first flower cluster. Prune all other suckers that grow on both stems.
3. For plants with three or four leaders, leave the first sucker or first two suckers above the first flower cluster. After that, prune off all new suckers.
The suckers should be removed when they are 2-3" long. In most cases, they will snap off when bent, although if the plant is wilted they may need to be pruned off with pruners or a razor blade. Pruning should be done about every week to 10 days to stay ahead of sucker development. If this task gets away from you and suckers get too long, you should pinch or cut off the growing tip of the sucker, leaving a few leaves behind, rather than trying to remove the entire shoot, which would create a wound close to the main stem and make it more vulnerable to disease.
For more information, see Johnny's video "How to Prune Tomatoes."
Training systemsOpinions vary about the best way to prune and train indeterminate tomatoes, with four primary strategies used by commercial growers:
Sprawl or ground culture involves neither pruning nor staking. Plants are left growing on the ground or on plastic mulch.
Cage systems involve pruning the plants to three or four leaders and confining them inside a cage.
Stake and Weave or basket weave requires plants to be pruned to one or two vines, and supported by twine strung between stakes beside every other tomato plant.
Trellis systems require plants to be pruned to two leaders that are tied to twine hanging from a wire stretched overhead.
Each system has advantages and disadvantages. Oklahoma State researchers compared the four systems and found that trellis culture, with the plants pruned to two leaders, resulted in the earliest and largest tomatoes and the best pest control. However, fruit cracking and sunburn were problems. Cage production resulted in the largest marketable yield, but ranked lower in earliness, fruit size, fruit cracking and rotting, and pest control. Ground culture was the worst in almost all measures. The system that seemed the best balance between yield and quality was Stake and Weave.
For more information, see "Training Systems and Pruning in Organic Tomato Production" by Oregon Tilth.
For information, read article on training hoophouse tomatoes in the Catalog Extras section of JohnnySeeds.com