Pest management in Conservation Agriculture

Realizing sustainable agricultural mechanisation

African Conservation Tillage Network

By: Peter Kuria

1 December 2017

Pest Management in Conservation Agriculture


Contents

1.Define pests, pathogens and weeds

2. Weed Management

3.Integrated weed management

4.Integrated insect and disease management

5.Weed identification exercise


Learning Exercises

• What are pests?

• What are pathogens?

• Give examples of pests and pathogens

• What are the damages caused by o pests and

o pathogens

to plants?

• What are weeds? What are the damages caused by weeds to crops?

• List the insect and pathogens control methods commonly used

• List the weed control methods commonly used


Introduction

• What are pests

o Organisms with characteristics that farmers see as damaging or unwanted - harms agriculture - feeding or

parasitizing crops and livestock.

• What are pathogens

o Microorganisms that cause diseases in plants and animals.

o In crops pests are weeds and/or insects and pathogens are bacteria, fungi, viruses or nematodes - damage the plant and cause disease symptoms.


Introduction – Weeds

• What are weeds

o They are plants that grow where they are not wanted/intended.

• Damage by weeds

o They are thieves: They take light, water and food away from your crops.

o They push the crops out of their living space.

o They shelter pests and diseases that attack the crop.


Characteristics of weeds• long dormancy period – up to 20 years high seed scattering ability

• high genetic diversity so adapted to wide range of conditions

• high rate of reproduction

• reproduction through both seeds and vegetative material

• vigorous and rapid growth

• ability to survive and reproduce under environmentally unfriendly conditions


Why controlling weeds?

• Competition reduced

• Weeds reduces crop yields and can lead to total crop failures if not controlled on time.

• Reduce Harvest quality

• The longer you leave them, the harder they become to control. Control them before they increase your cost of production, steal your yield hence income!


A weedy maize field


Striga weed on ploughed land?


Traditional means of weed control• Ploughing/ harrowing

• Stubble grazing

• Burning of crop residues (before ploughing)

• Hand weeding -Manual weed control is labour intensive and therefore limits the production area


Some examples of traditional ways of controlling weeds---- untimely

weeding -- increase of pest &disease incidences -- Increase cost of

production ---- low crop yield

Hand hoe weedingGrazing


Approaches for weed control in CA

Preventive weed control

• clean crop seeds and irrigation water– no weed seeds

• Use clean machinery

• preventing weeds from setting seeds

• Curing manure and compost

• Edges of crop fields should be weed free

Control techniques pre and post crop planting

• Cultural methods – intercropping, crop rotations, mulching, green manure cc,

• Physical control (mechanical and manual weeding).

• Chemical control through the use of herbicides


How CA reduces weeds• It disturbs the soil less, so brings fewer buried weed seeds

to the surface where they can germinate.

• The cover on the soil (intercrops, cover crops or mulch) smothers weeds and prevents them from growing.

• Rotating crops prevents certain types of weeds from multiplying.


Minimum soil disturbance-ripping Field well covered with Lablab


Integrated weed control options in CA

Usually a combination of two or more control strategies to increase effectiveness to economic levels

• Weeding by hand (pulling) or with equipment

• Use of soil cover and crops

• Use of herbicides


Hand Spraying Machine for Chemicals


Pedestrian (Hand pulled) sprayer ZAMWIPE


Animal drawn knife roller


Challenges to herbicide use

• Few farmers use herbicides.

• Profitability not established, land degradation risks not assured.

• Cash flow/liquidity constraints;

• Not easily available,

• Need special equipment and skills


Control of weeds under CA system: options for smallholder

farmers

1. Weeds can be a big problem when you first start using conservation agriculture.

2. You may have to work hard in the first couple of years to control weeds.

3. Be patient! If you do it properly, weeds will become less of a problem later on.

4. You can manage weeds in many different ways depending on the ecological and socio- economic circumstances of specific H/H.


Control weed cont…

5. Using crops and other forms of soil cover (green manures/cover crops and crop residues).

6. By hand pulling/weeding or using equipment to cut or crush the weeds.

7. Using herbicides.

8. Crop rotation

9. Planting density

10. In –row slashing of weeds

11. Superficial/Shallow weeding (scrapping)


Weed control strategy

• A weed control strategy with the greatest potential for success, is the one that fully integrates the many mgt options available.

• You will probably need to use a combination of these methods to control weeds. Example;

o One can start controlling weeds by using various forms of soil cover.

o These methods are cheap and avoid disturbing the soil.

o You can then kill any weeds that do grow by using a weed scrapper or machete, or with herbicides.


Mechanical weed control• Shallow weeding, Slashing, Uprooting,


Biological & cultural weed control

• Crop rotations, Intercropping (spreading crops), Cover crops.

Pearl millet under Faidherbia albida

Mzee Swaleh Shaaban admiring his crop


01/12/2017

A well established Mucuna crop providing a good ground cover


Chemical weed control

• Is common in commercial agric

• It can also be used by smallholder farmers esp in first years of changing from Conv to CA.

• Increasing labour shortage and cost of labour makes chemical weed control an attractive alternative for small farmers e.g. use of zamwipe, pedestrian sprayer, Knapsack

01/12/2017


When and how to control weeds – Steps in controlling weeds

Adapt them to suit your own situation.

1. It is a good idea to slash weeds immediately after the harvest and during the dry season to prevent them from producing seeds.

2. Before you plant, slash any plants (weeds, cover crop, stalks left over from the previous crop) in the field. (A disadvantage with this is that it may encourage grasses and certain other weeds to grow if it is wet.)

3. Dig planting pits with a hoe, or open planting furrows with a ripper or Sub-soiler.


When and how to control weeds: steps4. After the first rains have fallen, allow weeds to regrow or new weeds

to emerge. Wait about 2 weeks until they are growing vigorously, then apply a post-emergence herbicide such as R/up using a Zamwipe or a sprayer. This will kill all emerged weeds before you plant.

5. Immediately afterwards, plant the main crop.

6. Plant a cover crop between the rows of the main crop after two weeks (depending on the cc).

7. Check for weeds every week and control them by pulling them out by hand, scrapping the soil surface with a hand hoe/scrapper, using an animal-drawn weeder, or using a selective herbicides.


Steps cont’d

8. Harvest the main crop and allow the cover crop to grow.

9. Continue checking for weeds and pull them out before they can flower and seed.

10. Harvest the cover crop seeds.

11. Manage (bend over and crush) the mixture of crop residues and cover crops using a sickle, machete, knife-roller or another implement some 3 weeks before you expect the first rains to begin.

12. Cover crops that can regenerate should be slashed at 6-8 inches height.


Weed control in later years

• Weeds should be easier to control in later seasons.

• It can take 3–5 years for the number of weeds in the soil to be reduced so much that very few new weeds grow.

• Leave the soil undisturbed, and keep the soil covered so that weed seeds do not have a chance to germinate. Any weeds that are lucky to germinate have no space or light, so they die.

• You should still check for weeds regularly and pull out any you find.

• You may also need to use herbicides to control weeds.

But overall, weed control will be a lot less work.


Crop yield loss caused by delay in weeding

Crop Time delay in weeding Expected yield loss

Cotton 6 weeks 35-40 %

Soyabean 3 weeks 25 %

Groundnuts (rainfed) 5 weeks 320-430 kg/ha

Groundnuts (irrigated) 5 weeks 45 %

Maize 4 weeks 54 %

Sorghum 3 weeks 50 %

Egg plants 2 weeks 36-84%


CONCLUSION

1. CA does not necessarily mean use of herbicides.

2. Biological means, such as ground cover of crop residues and cover crops and rotation are efficient and preferred means of weed control.

3. Farmers noted that herbicides are used to overcome weed pressure especially in the transition period from conventional to CA.


Conclusions cont…

4. Environmental friendly herbicides are available

5. CHEMICAL WEED CONTROL IN COMBINATION WITH COVER CROPS AND CROP ROTATION CAN BE AN ANSWER TO INCREASING LABOUR SHORTAGE CAUSED BY MALE OUT-MIGRATION AND HIV/AIDS

01/12/2017


Pests & Diseases Control - issues• Disruption of the soil ecosystem by soil tillage upsets the balance

between pathogens and beneficial organisms, allowing the disease-causing organisms, which usually are more opportunistic, to become problems.

• The residues and cover crops that are preserved on the soil surface provide numerous habitats for insects and bacteria and fungi. In conservation agriculture systems more insects and micro-organisms occur as they are able to hibernate until the next crop.


Pests & Diseases Control - issues

• At the same time the cover provides habitats for natural enemies of pests and diseases occurring in commercial crops.

• Thus, conservation agriculture is a more natural system in which higher number of species occur; those that can cause damage to crops, but also beneficial organisms that predate on disease causing organisms, like higher parasitism on eggs of certain species.

• New balances between species are created, determined by the quantity of residues left on the surface and the crop rotation practiced.


Pests & Diseases Control

How to reduce the danger of pests and diseases-:

1. Rotate the types of crops grown - food, cover and cash

crops - interrupts their food supply and disturbs their living

conditions.

2. Select cover crops that are unlikely to be attacked by

pests/diseases e.g. canavalia, mucuna.

3. Plant various different types of cover crops.

4. Consider using chemical spraying if necessary.


Integrated Pest and Disease Management (IPM)

IPM is a set of strategies based on monitoring economic thresholds and preventive tactics to determine if and when pest treatment is best applied.

IPM follows a four-step procedure:

o setting action thresholds

omonitoring and identifying pests

oPreventing

ocontrolling


Learning activity

Give 2 examples of weeds that are common in your working area for each of these categories.

Broad leaf, Grass weeds, sedges, parasitic weeds, noxious weeds.

Discussion points:

• Which weeds are associated with low soil fertility, and which ones with high soil fertility?

• Are there weeds that remain green during the dry season – worth considering as soil cover crops? Are all the weeds edible for humans and livestock?

• Which weeds die naturally after one season and are easier to control? Which ones are difficult to control?

• State suitable control methods used for each weed.


MLN disease in Laikipia, Kenya


01/12/2017

moist

soil

Example #1

Burning organic matter and losing soil water.

Men ploughing

dry

soil


THANK YOU


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Pest management in Conservation Agriculture

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