STATUS OF WEED CONTROL AND HERBICIDE USE BY SMALL COMMERCIAL VEGETABLE GROWERS IN KENYA

Reports from the government and other development partners on the status of agricultural production indicate that small scale farmers are major actors in agricultural productivity.

It has been established that over seventy percent of the country’s agricultural production occurs in small farms; from tea, coffee, vegetables and fruits among others.

At the moment, farmer’s fortunes are being changed by the increased demand for vegetables for the local and export market caused by a ballooning population in urban areas and shortages due to extreme environmental changes.

Unfortunately small vegetable farmers lack technical information on the use of herbicides and other technological innovations that are available to large scale farmers.

Many small farmers rely on manual methods of weeding like; the use of hoes or ox-driven ploughs, therefore they can’t effectively control weeds when they increase the area dedicated to vegetables.

This backbreaking custom of using Iron Age implements, limits the productivity of small vegetable farmers. Farmers are unable to control weeds during the critical first 3-4 weeks [when there is rapid weed growth] during the rainy season.

As vegetable production areas have continued to increase, labor supply has decreased due to urban migration of the educated youth. The youth move to urban centers for better paying jobs or to do small trading rather than work in the fields where the pay is meager.

This has led to inadequate supply of labor for weed control and increased labor costs during the peak labor requirement period when some farmers are still sowing and weeding their first crop.

Small commercial vegetable farmers have realized, vegetables are a high value crops; they are considering other methods of weed control rather than limit the area planted to vegetables.

Some are now using herbicides to control weeds in vegetables with varying levels of success. A study was conducted in three divisions in central province; known for vegetable production.

The survey was conducted in; Kabete, Lari and Kinangop divisions because intensive commercial vegetable growing is practiced. All farmers in the areas owned 1.5 to 2.5 hectares.

During the study, the following herbicides were used by farmers

1. Afalon –used to control weeds in coriander, onions, carrots

2. Sencor-used to control weeds in tomato

3. Stomp-used to control weeds in cabbages

4. Gramoxone-used in fallow land

Farmers said that herbicides helped them expand the area planted to under vegetables. Farmers said they often weeded 3-4 times before each crop matured and was ready for harvest thus they would not be able to afford labor for hand weeding.

When asked how they came to know how the herbicides are used, most of them said they were taught by other farmers. Some of them said they were taught on herbicide usage by the vendors of the product.

This finding indicates that there is a need for extension officers to educate farmers in the areas. Unfortunately this may not be realized because the government rarely employs extension officers.

There is a need for farmers to organize themselves in community based organizations to take advantage of the few extension officers available. The NGOs involved in rural role need also to take a proactive role in assisting farmers.

Physiology, fruit initiation, environmental conditions and yield of strawberry.

It has been noted; the physiology of strawberry plant,the environmental conditions where strawberry is grown, how strawberry is established in the field, the use of plastic mulch on strawberry, thinning of strawberry runners determine the yield per acre of strawberry plants.

My focus is to give a brief explanation on how the aforesaid conditions interact to determine the yield of strawberry and the practices a farmer can follow to maximize the yields of strawberry plants.

Physiology of strawberry plant

Strawberry is a compressed woody herbaceous perennial plant that produces stolons from auxiliary buds on the second node.

This means that the plant can survive for more than one season and the plant is propagated vegetatively.

Branches may form at auxiliary buds; at times, the bud produces an inflorescence or remains dormant depending on environmental conditions.

It has been observed that the roots produced by the plant don’t go deep in the soil; 50-90% of them are found in the top 15 cm of the soil.

New roots grow above old roots, this makes it necessary to cover the plant roots with more soil after harvesting otherwise they will  dry and the consequence will be poor subsequent harvests.

The fruit  produced heart shaped and appears to be tri-lobbed symbolizing trinity. The shape of fruits varies; some are oblate or globular, but the common fruits are heart shaped.

conditions favoring FRUIT INITIATION OF STRAWBERRY

Short days and temperatures of 20-24⁰ C are some of the conditions that induce flower initiation.

If weather is warm throughout the year, blooming is continuous. Too cold or too hot temperatures inhibit flowering.

It has been discovered that growing conditions experienced by the plant during flower initiation and pollination determine the size and quality of the berries.

Any thinning or frost damage after flower initiation does not change ultimate size of berries. This is because the cells in the fruit have divided and their number fixed.

Fruit development starts when  fruit-lets develop on the surface of the receptacle after the terminal buds produce an inflorescence.

Achenes are present in the receptacle; their purpose is to produce auxins [a hormone]  responsible for fruit expansion; some auxins e.g. 2-4-D over-stimulate fruit expansion.

First flowers to be produced by the plant give larger fruits; such flowers are known as king flowers.

 

STRAWBERRY ESTABLISHMENT

Each plant produces 15 stolons that survive up to 3 weeks before they die. Stolon production is very important for crop multiplication.

Once the stolons are produced, they are cut off and used to produce new plants.

Spacing between plants and rows varies but one that is used is 60 cm between rows and 40 cm between plants.

The beds are raised above the ground to reduce the splashing of rain or irrigation water on the plants that encourages foliar diseases.

 

PLANTING of strawberries

The land should be prepared thoroughly to a fine tilth.

Mix compost or well decomposed farmyard manure with the top soil in the planting bed.

Mix 200 kg of Double Super Phosphate (DSP) fertilizer per hectare if the beds have the dimensions of 1 Meter by 40 Meters.

The beds should be raised so as to improve soil drainage and control root rot diseases.

Plants should be soaked in water for at least 10 minutes before planting and should be planted as soon as possible.

The roots should be spaced out so that they establish easily in the soil and ensure the soil is at the crown level to avoid rotting.

If you plant the crop shallowly; roots will be exposed and dry easily. The plants should be firmed well daily, until they are well established.

 

USING PLASTIC MULCH ON STRAWBERRY

Runners can also be planted through plastic mulch however, this increases production cost. Make holes on mulch and let the runners touch the mulch.

If watering is done under mulch, black mulch warms the soil resulting in early flowering and suppression of weeds.

Clear plastic mulch allows light to reach the beds, thus weeds continue growing but it has the advantage of preventing frost. If you are using plant covers, they should be removed when flowering starts.

Straw mulch protects the plants against cold injury. They should be placed on top of the plant late in the season as the plants go dormant. Straw mulch is removed early in the next growing season. Strawberry can be grown hydroponically.

 

THINNING OF RUNNERS IN STRAWBERRY

After planting, runners should be trimmed off so that they channel energy into vegetative growth first. The flowers should be removed for the first 4-6 months to allow adequate runners to develop first.

Once flowering starts, you need one to two rooted plants for the next planting.

Strawberries produce few runners so spacing is close. The beds should be replanted every 2-3 years using disease free runners. The lifespan of strawberries is 3 years.

Weeding should be done by cultivating shallowly in between the rows. Other types of mulch e.g. straw that will smoother the weeds, other alternatives are using of herbicides.

 

HARVESTING AND YIELDS

Harvesting is done regularly three to four weeks after flowering; start targeting green to light brown/red fruits. Handle the fruits carefully to avoid bruising them.

You can harvest 12-15 tones of strawberry per hectare if the crop is managed well. After harvesting, old leaves are cut off after duration of 3 months.

Cutting off old leaves helps in controlling diseases and results in new clean growth. Irrigate and apply a nitrogenous fertilizer at a rate of 200 kg of DSP after harvesting.

HANGING BASKETS

Hanging baskets or flower pots are movable gardens floating in the air above the eye level, showing off the best plants by spilling the trailing branches in all directions.

The most effective display technique of hanging baskets is that of drooping, trailing and spreading plants and using the upright plants to show off the plants at their best.

Hanging baskets should appear pleasing to the eye from a short distance, from all angles.

You can add a new dimension in indoors or outdoors living decorations by arranging flowerpots containing beautiful plants at the ground level to enhance the visual appeal of the hanging baskets.

Plants supported from the ceilings, patio, trees or shrubs create a means of adding interest in undecorated areas. The hanging baskets should be viewed from all sides above at the level.

Hanging baskets on patios add a cheerful note to outdoor entertaining, while a burst of color at the front door provides a warm welcome.

The secret to great looking containers is to keep them well stocked, overflowing and abundant with flowers.

CHARACTERISTICS OF PLANTS SUITABLE FOR HANGING BASKETS

They should be trailing, creeping and have excess branching.

For example:

A. Maiden hair fern- epipremnum aureum

B. Money plant- Adianthum sp

C. Nerve plant- Fittonia sp.

D. English ivy- Hedera helix

E. Vine philodendrons- Philodendron sp

F. Pilea muscosa

G. Wax plant hoya cannosa

H. Mother of thousands-saxifrasa sp.

I. Sedum morgarianum

J. Swedish ivy-Plectanthus australis

PLANTING

It is advisable to use a thin layer of moss plants on the inside the flower pots. This layer of moss plants and plastic sheeting should be pierced so as to allow water to percolate to the soil.

Small tray or saucers should be kept at base of baskets as this prevents water from dripping from the pot to the surrounding walls or ground thus mud streak marks don’t appear on the walls.

There is no special purpose soil or compost for use in hanging baskets; any potted soil mixture is suitable with the exception of heavy clays.

METHOD OF PLANTING

Select plants to be grown in the baskets bearing in mind, the location of the basket; whether, in the shade or in the sun

Always use strong and healthy plants, free of pests and diseases. Aphids can spread very fast in the baskets.

Besides trailing ivies and perennial vines, some annuals and flowering plants can be grown effectively in baskets for example;

A. Verberna hybridus

B. Petunia hybridus

C. Phylox drammendi

D. Allysum maritinum

Plant large plants at the centre of the hanging baskets and place the smaller ones and trailing ones around the basket.

After putting the plants in position; firm the soil around the plants, adding more soil if necessary.

Level the surface to slope slightly inwards towards the centre of the pot to prevent water from overflowing.

After potting, soak the basket in a large bowl of water for about half an hour after which the basket is ready for hanging out.

LOCATING A HANGING BASKET

The location of a hanging basket is determined by the plants tolerance to shade or full sunlight.

For example, flowering plants and non shade tolerant plants will need to be placed near bright window in outdoor living areas e.g. verandas and patio.

Foliage plants which are shade tolerant may be placed in cooler areas of the house e.g. staircase or near the corners of house to soften the architectural lines.

Locate hanging baskets in areas where, they will not restrict traffic movement in the house or where the pots may be viewed to the greatest advantage i.e. at eye level and should be grouped according to light and temperature in a room.

Many house plants grow rapidly in a trailing manner. This means they don’t grow inwards or fill the centre of the pot.

It is therefore important, to have a mixture of climbing plants and upright flowering plants in the same hanging basket; upright plants placed at the centre create interest to the hanging baskets.

Soil media should be light in weight so that can be supported by hanging basket.

MAINTENANCE

Hanging baskets need frequent watering and even daily airing. They should be never put in a drought free area, they need lots of air!

Do not put hanging baskets in dark corners of a room; the plants will sulk, become dark and grow slowly.

To keep the plants in a good shape always, cut the dead ends and remove dead leaves. If they grow too long, trim and pinch the growing tips.

Fertilize the soil once in three weeks with bio liquid fertilizer to enable the plants grow better and healthy. Check regularly for any disease or pest attack; if any symptoms are observed, spray in timely manner.

Rotate the position of the basket every month to enable a uniform growth on all sides of the basket.

RECIPE FOR RED HOT HUES

These plants require morning sun to full sun

1. New Guinea fanfare, impatiens orange

2. Asparagus fern

3. Petunia million bells terracotta

4. Snapdragon Luninae

5. Yellow verberna

RECIPE FOR PASTEL SHADES

These plants require Semi-shade conditions or the morning sun

1. Plectranthus ‘muna lavender’

2. Alternathera ‘purple knight’

3. Verbarna ‘aztec white’

4. Pink nemesia

RECIPE FOR A TOUCH OF CLASS

These plants grow best in full shade

1. Impatiens fiesta ‘ole peppermint’

2. Impatiens super elfin ‘lipstick’

MORE PLANT IDEAS

Most plants prefer the morning sun and afternoon shade, but some will tolerate hot sunny conditions.

A fair number will grow in partial or filtered shade while only a few [select] will thrive in shady conditions.

Once you choose location for containers make sure you choose the right plant.

Plants that thrive in full sun: alussum, celosia, cosmos, dianthus, marigold, narsturtium, petunia, portulaca, salvia, sunflower, zinnia, rudbeckia, verberna, arctotis, coreopsis, Felicia, Gaura, Gazania, lavender, Pelargonium.

Those that thrive in the morning sun: abutilon, aquilegia, fuschcia, lobelia, nicotiana, schizanthus, torenia.

Those that thrive in Shade conditions: Begonia, Coleus, Impatiens.

TIPS FOR SUCCESS

1. Line hanging baskets with coir mats to conserve moisture.

2. Fill or top-up your pots with good quality potting soil. In hanging baskets, use indoor planting soil as it retains moisture well.

3. Add water retaining gel to the soil.

4. Take into account whether the container will be in sunny or shady positions and choose your plants accordingly.

5. Hanging baskets perform better when placed in partially shaded to shady positions.

6. For best effects limit the number of colours used to a maximum of three.

7. Choose shades that harmonise or contrast with each other.

8. Choose plants that suit the container. A low container will focus on the plants, while a decorative pot can be as much part of the display as the plants it holds.

9. While a decorative pot can be as much as much part of the display as the plants it holds. Trailing plants suit a large container and hanging baskets.

10. Plant taller plants in the centre of the container and lower growing ones around the edges.

11. Remove flowers that have finished blooming regularly in order to prolong the flowering season.

12. If you buy an already made up basket, it is best keep it in semi-shade because full sun will be too harsh.

13. Groom your baskets and containers regularly if the baskets starts to look a little ragged don’t be afraid to cut the plants or replace them.

Cumin

Cultivation of this crop in Kenya limited because of lack of information on planting, cultural practices and control of the diseases like alternaria blight that appears in an epidemic form.

India is the leading country in the world in terms of production, consumption and export of cumin.

Though  is an important spice crop with high economic returns, its cultivation has not taken place in areas where it can grow well.

USES AND IMPORTANCE of cumin

It is used in the preparation of a number of medicines; it is a good carminative  for controlling diarrhea and astringent digestive disorders.

It is also used in veterinary medicine, in the manufacture of cosmetics, curry powder, culinary preparations, and spice blends and  beverages.

ENVIRONMENTAL REQUIREMENTS

The plant grows well in cool and dry weather; heavy rains during the growth period damage the plant.

On the other hand warm weather increases the incidence of the disease attaining an epidemic form at flowering and seed formation.

Frost or cool air also affect the flowers negatively-all these factors combined, result to shriveled seeds.

FIELD PREPARATION

A very fine seed bed should be prepared; to achieve a fine seed bed in loamy soil, 3-4 deep plowings should be done followed by harrowing and leveling.

The field should be kept free from water logging by providing suitable draining channels.

VARIETIES OF CUMIN

1. MC 43,

2. RS 1,

3. RZ 19,

4. Gujarat cumin 1.

SEED AND SOWING

The selection of seed, seed treatment, sowing time and method of sowing are the important practices that influence the production of cumin.

About 10-12 kg of healthy treated seed is required for 1 hectare.  The seed is treated with any suitable fungicide like agrosan or cerasan at the rate of 2 grams for every kilogram of seed as a precaution against the seed borne diseases.

The best time to sow cumin seeds in Kenya is from the mid October to the mid November. It has been noticed that early sowing prolongs the vegetative period and increases incidence of cumin blight.

Late sowing in December is preferred to produce high quality seed. The seeds are very small in size, so very careful sowing is required for constant distribution of seed on the farm.

Seed can be broadcasted or dropped in lines by specially designed mechanically operated seed drills.

The recommended spacing between the furrows is 30 cm while between the plants is 10 cm. Space, between the plants is adjusted through thinning operations 15-20 days after sowing.

MANURES AND FERTILIZERS

The addition of 10-15 tones of well decomposed farmyard manure month before sowing the seed improves the tilth of the soil making it desirable for a cumin.

Under rain fed conditions, 20 kg of Nitrogen and 20 kg of phosphorous should be applied as a basal dose. The remaining 20 kg of nitrogen is applied in form of a foliar spray. after  rains commences.

Under irrigated conditions, 30 kg of Phosphorus and 20 kg of potash are applied in the split doses; one after irrigation, the other during the early stage of vegetative growth or as a foliar spray with 2% urea.

WEED CONTROL

Weeding should be done in the early stages of the crop growth to reduce competition of weeds with the crop for the soil moisture, nutrients and sunlight.

Weed control can be achieved by hand hoeing after 15-20 days of sowing or spraying of herbicides like isoprotun at the rate of 1 Kg of active ingredient in 800 liters of water as pre-emergence application.

IRRIGATION

Adequate field moisture is necessary for the germination of the seeds. Cumin seeds germinate within 9-10 days after sowing depending on the soil moisture levels.

Irrigate frequently at an interval of 10-15 days taking care no water logging occurs in the field. After flowering, one, light irrigation is given and the crop is left to mature.

HARVESTING AND THRESHING

The crop is ready for harvesting in 90-130 days. Harvesting is generally done early in the morning to avoid shedding of the seeds.

Harvesting done by uprooting the whole plant; the harvested crop is spread out on the threshing floor to dry in the sun for 2 days, after which threshing is done by beating lightly with a stick.

YIELD

5-12 quintals per hectare (500-1200 kg) are produced under good climatic conditions if the crop was without any epidemic diseases and pest damage.

The yield of volatile oil from the mature seed ranges from 2-3% by weight and a strong aromatic greenish oil to an extent of about 10%.

diseases of cumin

Cumin is attacked mainly by fungi which cause two serious diseases;

1. Cumin blight disease
2. Powdery mildew

cumin blight 

The disease is caused by alternaia species and  appears during warm humid weather taking an epidemic form at flowering stage.

The seed is affected to the extent that they can’t mature to the full size where seeds mature,they become shriveled and are easily blown during winnowing.

It has been observed that early sown crop makes is highly susceptible to the disease; producing unmarketable seed.

To control the disease,  a foliar spray of difolan or dithane M45 effectively reduces the disease incidence.

Spray the crop repeatedly with cuman at the rate of 100 ml in 100 liters of water or spray the crop with Bordeaux mixture 1%.

The first spray should be 3 weeks after sowing and subsequent 3 sprays at intervals of a fortnight.

Powdery mildew

This disease is also caused by a fungus in warm humid climate, a white growth of fungus mycelia is visible on the ventral and dorsal surface of the leaves and the stems.

flowers are malformed and covered with white powder and no seeds are formed.

To control the disease, the crop is sprayed with fine sulfur at the rate of 20kg/ha in two doses; the 1st with the onset of flowering and the second after 10 days.

After 2 or 3 days spray cosan at the rate of 100g in 100 liters of water at fortnightly intervals from onset of flowering.