How should I manage weeds and the orchard floor?
There are two surfaces with two jobs: a clean strip where the trees are, and a working floor everywhere else.
The orchard floor is two surfaces, and they have different jobs.
The tree row
- Where your young trees are getting established.
- Anything growing there is taking their water, their nutrients and their light.
- Keep it clean.
The row middle
- The strip between the tree rows, and your working surface. It carries the sprayer, the mower, the shaker (the machine that shakes the nuts loose) and the harvest trailer.
- At the end of the season, it has to let you sweep up the nuts cleanly.
- It can also protect your soil.
Why the floor matters
| What it affects | What it costs you |
|---|---|
| Competition | Weeds take water and nutrients from young trees, and they shade them. The effect is worst in the first four years, when the tree has a small root system and cannot compete. |
| Water | Anything green is using water. Vegetation also changes where the water goes, and it hides leaks and blocked emitters (the small outlets on a drip line). |
| Soil | Plant cover protects the soil from erosion, crusting (a hard crust on the surface), runoff and dust. Bare soil that is worked again and again loses its structure (the crumb-like way that soil particles hold together). |
| Access | A stable middle lets you take machinery in after rain. A middle with ruts and clods (hard lumps of soil) does not. |
| Animals | Weeds around trunks give voles and mice a place to hide, and they chew bark. Rodents that girdle a young trunk (chew the bark all the way around it) kill it, and rodents that chew drip lines waste your water. |
| Harvest | Tall weeds, loose residue (cut plant material), clods, holes and wheel ruts all cost you nuts at pickup. Pickup is the stage where fallen nuts are gathered off the ground. Once the trees are bearing (producing nuts), that is a direct loss. |
The tree row
Judge the width by where the tree’s roots and water are, not by a number. The strip needs to cover the wetted zone (the soil that your irrigation water reaches) that the tree draws from. It does not need to be wider than that. Bare soil across the whole orchard is a cost, not a goal.
Three rules for the strip
- Keep the trunk zone completely clear. This is where voles and mice hide, and where they do their damage.
- Do not cultivate (work the soil with tools) close to the trunks. Discs and other mechanical tools cut roots and strike the bark. Every wound is a way in for crown and root disease (disease at the base of the trunk and in the roots). Control weeds near trunks by other means, and keep your implements (the tools that you pull behind a tractor) a safe distance from the trunk.
- Check the wetted zone separately when you inspect. Weeds around an emitter change how much water the tree receives. They also hide a leak or a blockage until the tree shows stress.
Herbicides on young trees
Young trees are much easier to damage than mature ones, and fewer products are registered (officially approved) for use on them. Your own country’s registrations decide which products you can use, and these change every year. Ask locally. The technique works in any country.
- Green bark is not protected bark. A young trunk is still green, and contact herbicides (herbicides that damage whatever green tissue they touch) can damage it. Leave the trunk guard or carton in place for the first two years after planting, or until the trunk gets too thick for it. A carton is a cardboard sleeve that does the same job.
- Watch for drift (spray blown by the wind onto the trees). Branches on young trees are low and easy to hit. Be careful in wind, and check your sprayer height, nozzle angle and nozzle choice before you start.
- Wait for the soil to settle. After planting, the soil around the tree is loose and the roots are shallow. A soil-applied herbicide (a herbicide that you apply to the soil) can run down a crack or into a loose pocket and reach the roots. Let the soil settle first, and water carefully so that you do not wash the herbicide deeper.
- If you are building mounds of soil along the tree rows, do not do it just after a herbicide application. You will gather treated topsoil into the mound and concentrate the herbicide exactly where the roots will grow.
Three steps, in this order
- Identify the weed.
- Choose a product that is registered locally and works on that species.
- Apply it properly, with equipment that is calibrated (checked so that it applies the right amount), at the right growth stage.
The row middle: choosing a system
Five options, and none of them is right everywhere.
| System | What it gives you | What it costs |
|---|---|---|
| Clean, bare middle | Pickup is predictable, the floor is easy to inspect, and no live plants use water. Suits flat sites with little erosion, and systems that need a very clean harvest surface. | Repeated tillage (working the soil with machines) roughens the soil, increases erosion and dust, damages the soil structure and builds wheel ruts. |
| Mowed resident vegetation | Whatever grows naturally, kept short. It disturbs the soil very little, gives machines traction (grip), and is cheap and flexible. | It still uses water, it will produce seed if you mow late, and it gives rodents a place to hide. |
| Planted seasonal cover crop | Sown for a purpose: erosion control, better wet-weather access or better soil condition. | Seed, establishment (getting the crop to grow), management and water. |
| Permanent vegetation | Continuous cover, traction and the least erosion. | The strongest and longest-lasting competition with the trees. Does not suit young blocks or blocks with limited water. |
| Mulch on the strip | Mulch is a layer of material spread on the soil. It is useful in particular situations. | Where the material comes from, the cost of spreading it, weed seed and contaminants in it, fire risk, and the rodents it will shelter. Keep it off the trunk itself. |
Mowing
Decide when to mow by the purpose, not by the calendar. If you mow early, you stop the weeds from producing seed, but they regrow before harvest. If you mow late, you leave cut material lying on the ground exactly when you need a clean surface.
Cultivation
Cultivation (working the soil with tools) still has a place, for annual weeds (weeds that live for one year) and for mixing material into the soil. But a pass (one trip over the block with a tool) can remove every visible weed and still be a bad decision. That happens if it leaves clods, ruts, dust, erosion or a wounded trunk.
Annual and perennial weeds are different problems
| Weed group | What it takes to control them |
|---|---|
| Winter annuals | Inspect early and treat while the weeds are small. Waiting until the growth is dense makes every option more expensive. |
| Summer annuals | Watch the block after irrigation and after rain. These are what trigger a new burst of weed growth. Growers who plan only a spring programme are surprised by this group. |
| Creeping perennial grasses Bermuda grass (Cynodon dactylon), Johnson grass (Sorghum halepense) | Map the patches. Treat at the stage when the plant is moving its food reserves down into the roots. Take care not to drag fragments of the plant to clean ground on your implements. One treatment is not control. |
| Deep-rooted perennial broadleaves (weeds that are not grasses) field bindweed (Convolvulus arvensis) | You need repeated work, with treatments chosen for each species. If you treat the tree row and ignore the field boundary, the weeds only return later. |
| Nutsedge (Cyperus species) and other wet-ground weeds | Fix the water as well as the weed. Where you find nutsedge, look for the cause: a leak, an over-watered zone or a drainage problem. |
Cover crops
A cover crop has several benefits. It adds organic matter, reduces erosion and runoff, reduces crusting and dust, improves access in the wet season, and holds back winter weeds to some extent. Legumes (the pea and bean family) add some nitrogen.
Before you sow
- Plan for its water use. The question is not whether cover crops are good. The question is whether this block can support one without taking water from the trees. Competition matters most in young orchards, on shallow soils, where irrigation capacity is limited, and in dry years.
- Do not grow a cover on the tree row of a young orchard. The one thing to avoid is competition for water between the cover and a young tree in summer. Keep the cover in the middle.
- Sow in autumn, so that the cover uses the season’s own light and water instead of yours.
Once it is growing
- Kill it early enough. Killing the cover around May reduces early-season water stress on the trees. Where you have no irrigation water to spare, mix the cover into the soil in spring so that the water goes to the trees.
- It holds back weeds. It does not replace weed control. No orchard with a cover crop is weed-free. Continue the tree strip programme and the patch programme.
- Do not assume a fixed amount of nitrogen from a legume. The amount depends on the species, how much plant material (biomass) grew, and when it breaks down.
- Mow the cover. An unmown cover is an excellent habitat for burrowing rodents. If you use covers, your monitoring for pest animals such as voles and mice has to be better than it would be without a cover.
What to do at each orchard age
| Orchard age | What belongs in the middle |
|---|---|
| Years 1 and 2 | Clean tree rows are the priority. Keep anything in the middle low-risk, and plan its water use. |
| Years 3 and 4 | Try controlled vegetation (vegetation that you manage) in some row middles, where water and machine traffic allow it. Do not use it on the whole farm before you have seen it work on your own soil. |
| Mature orchard | Use permanent or seasonal cover where your water supply and your harvest system can support it. |
Nothing in our source material names a cover crop species suited to a Turkish, Balkan or Central Asian orchard. The advice above to sow in autumn and to end the cover around May comes from a French source. Ask a local adviser what to sow before you buy seed.
Building the harvest floor
Mechanical harvest needs a surface that you can blow, sweep and collect from without losing nuts or picking up dirt. Tall weeds, heavy residue, clods, ruts, holes, damaged berms (the raised strips of soil along the rows) and leaks all cost you at that moment.
| When | What to do |
|---|---|
| Through the season | Avoid the machine traffic and cultivation that create clods and deep wheel tracks. Repair damage while conditions allow it. |
| Before harvest season | Walk the block and map ruts, holes, irrigation leaks, tall weeds, perennial patches, woody debris, damaged berms and low spots. Fix them while the schedule is still flexible. |
| Before final floor preparation | Mow the vegetation that you have kept, early enough that the cut material settles and does not regrow. |
| At final preparation | Smooth the surface without overworking it. Protect drip lines and roots. |
| Just before shaking | Walk the block again and look for debris, new growth, leaks and soft ground. Test pickup in one typical area before you start on the whole block. |
| After harvest | Write down where pickup was poor and why. That is your work list for next season. |
Mistakes worth avoiding
The trees
- Letting weeds compete with young trees. The first four years are when it costs most and when the tree can least afford it.
- Treating the tree row and the middle as one zone. A cover that helps the middle can starve a young tree at the trunk.
- Cultivating too close to trunks. Every wound is a way in for crown and root disease.
- Spraying a young green trunk. Keep the guard on for the first two years.
- Sowing a cover crop without planning its water use. It is a crop, and it will take the water that it needs.
- Leaving a cover unmown. You have built habitat for burrowing rodents.
The floor
- Cultivating too much. You roughen the floor, increase dust and erosion, and create harvest work.
- Spraying without a plan. Identify the weed, check what is registered, calibrate the machine, and treat while the weeds are small.
- Using the same product every year. The weeds that survive it are the ones that spread.
- Mowing too late. Cut material lying on the ground is lost nuts at pickup.
- Treating the tree rows and ignoring the ditches and margins. The weeds come straight back.
- Fixing the floor at harvest time. Ruts and clods are cheap to prevent and expensive to repair when you are short of time.
Choosing your floor system
Eight things to decide for each block
- Whether the block is in its first four years. If it is, the clean tree strip is not optional.
- How much water you can spare for vegetation in the middle, in a dry year as well as in a normal year.
- Whether erosion, runoff or wet-season access is a real problem on this block.
- Which machines have to work in the middle, and what surface they need.
- Which weed species are the most common, at what time of year, and where the patches and the edges are.
- Whether your plan for mowing and for ending the cover crop fits your harvest date.
- Whether you have a plan for monitoring rodents, especially if you are using a cover.
- What is registered locally for young trees, and whether the people who spray are trained and your sprayer is calibrated.
Work through this list block by block, not for the whole farm at once. The answers change between a first-leaf planting (trees in their first growing season) and a mature block on the same farm.