Letters to the editor: What to do to stop tomato diseases in greenhouse

UNDERSTANDING TOMATO DISEASES

I do have a greenhouse in Kakamega. I grew tomatoes and capsicum. The tomatoes started to fruit well, but later wilted one by one. I tried again but the problem recurred. The green house has stayed idle for years now. I want to start farming tomatoes gain. I have taken soil for analysis and I have been told to fumigate the greenhouse. Which chemical fumigant can I use that is available in our market? Please assist me to make a living from this farming.
Lugalia Benson

Response one

This is a tomato disease called Bacterial Wilt caused by bacteria called Pseudomonas solanacearum. The disease is characterised by rapid wilting of the plant and when the stem is cut across, slimy substance oozes out and the pith may be dark or water soaked in appearance.

Pathogen is soil-borne therefore that means it is still in the soil in your greenhouse and the only solution is to fumigate the greenhouse and practice hygiene in the greenhouse.

Several fumigants are available in the market: chloropicrin (tear gas), methyl bromide, metam- sodium, basamid, methyl isothiocyanate and many others.

Carol Mutua, Department of Crops, Horticulture and Soils, Egerton University

Response two

Please find out first, the outcome of the soil analysis from where you tested the soil, because it may have been bacterial, fungal or nematode problem. Fumigation is meant to reduce soil born pests and diseases.

You can use fumigants available in your market but find out what you are targeting. Bacterial wilt or Southern bacterial blight is a serious disease caused by Ralstonia solanacearum.

Fusarium wilt is a warm-weather disease caused by the fungus Fusarium oxysporum (soil born).

The first indication of disease in small plants is a drooping and wilting of lower leaves with a loss of green color followed by wilting and death of the plant.

Often leaves on only one side of the stem turn golden yellow at first. The stem of wilted plants shows no soft decay, but when cut lengthwise, the lower stem will have a dark brown discoloration of the water-conducting vessels.

The fungus is soil-borne and passes upward from the roots into the water-conducting system of the stem. Blocking of the water-conducting vessels is the main reason for wilting.

Invasion occurs through wounds in roots growing through infested soil.

Long-distance spread is through seed and transplants.

Control: Control can be obtained by growing plants in pathogen-free soil, using disease-free transplants and growing only cultivars at least resistant to races 1 and 2 of Fusarium wilt (indicated by FF following the tomato cultivar name).

Raising the soil pH to 6.5 - 7.0 and using nitrate nitrogen (such as in calcium nitrate) rather than ammoniacal nitrogen (as in 5-10-10, 10-10-10, or 34-0-0) will retard disease development.

Lastly, Root-knot nematodes (Meloidogyne species) are microscopic worms that live in the soil and in plant roots. Affected plants are usually stunted, discolored and may die.

Knots or galls develop on the roots. Galled tomato roots caused by root-knot nematodes (Meloidogyne species). Confirm this by uprooting one tomato plant and check for the galls.

Prevention & Treatment: When nematodes are not yet present, change the garden location every year, pull up and dispose off roots immediately after harvest.

When root-knot nematodes are present, relocate the garden to a nematode-free area. Establish a rotation system using marigold cultivars Tangerine, which reduce root-knot nematode populations in soils (in case nematode is the problem).

Soil Fumigation and solarization (heating wet soil, covered by clear polythene) are recommended for Nematode reduction.

Peter Caleb, Horticulture Scientist, Department of Crops, Horticulture and Soils, Egerton University

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LOOKING FOR TISSUE CULTURE BANANAS

I kindly wish to know where I can source tissue culture bananas especially around Nakuru.
Mohammed Magut

Please visit KALRO Kandara on the tissue culture variety you may need. Contact them early enough to book on 0720836787.

Peter Caleb, Horticulture Scientist, Department of Crops, Horticulture and Soils, Egerton University

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IN SEARCH OF A VET

I am a dairy goat farmer at Nakuru Ngata area. I have a problem getting a veterinary who knows about goats’ health and breeding. Kindly refer me to one.

Can I get these services/ advice on dairy goat farming from Egerton University?

Gladys Mwangi

The University’s Faculty of Veterinary Medicine is made up of qualified personnel who offer expert advice across value chains, including farmers.

Breeding for instance, is artificial insemination in goats with high quality semen for Saanen and German Alpine breeds.

Get in touch through [email protected] or telephone number +254- 51-221-7684/5.

Felix Akatch Opinya, Department of Animal Sciences, Egerton University

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IS MOLASSES HEALTHY FOR MY MILK COWS?
I have used molasses as an additive in my dairy feed and I see very positive results. There is better milk production and the animals look healthy and energetic. I met a friend who told me molasses destroys cows’ teeth.

Is it true? If it is so, then what is the safe alternative?
Bor

Molasses is a used in livestock feeding during silage making, feed pelleting as binder, source of carbohydrate and to increase palatability of fodder. It comes with no side effects if used in right proportions.

However, if fed in large amounts, cows can fall prey to molasses toxicity with general symptoms including a drop in body temperature, weakness with unstable gait and rapid breathing.

Supplementing molasses at high levels is mostly known to cause diarrhoea and bloat if fed together with succulent fodder. Therefore, only a required amount depending on the feed should be diluted and utilized at one feeding.

Felix Akatch Opinya, Department of Animal Sciences, Egerton University

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RABBIT URINE MARKET

Thank you for the good work you are doing in interlinking farmers, markets and technology. I am a keeper of rabbits at the coast. My request is that you link me to market for rabbit urine.

I highly appreciate your prompt response and your dedicated support in terms of information.

Antony Musyoka

Rabbit urine is highly corrosive so one must use rust proof materials during pen construction to collect enough urine and make good money when sold.

The urine is known for manufacturing organic liquid manure in a bid to reduce reliance on fertilizers like DAP, CAN and NPK. One company that buys rabbit urine in Kenya is the Kenya Com Rabbit Consortium Limited, email them on [email protected] or call 0725 600 710.

Felix Akatch Opinya, Department of Animal Sciences, Egerton University

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WHY MANGO YIELDS DROP?
I planted 20 mango trees on two acres in Malindi and had a good harvest in the first season, but last season, my yields dropped. I want to know:

1. What part of the mango tree needs pruning most?
2. What manure and fertiliser should I use, and how frequently?
3. How frequently should I water a mature tree?
4. What chemicals do I use to spray trees?

Bhardwaj

The phenomenon of good harvest in one season and a drop in the next one is referred to as biannual or alternate bearing/fruiting.

It is influenced by many factors including environmental (humidity, water, temperature and diseases), genetic and cultural (soil fertility).

The problem can be managed by avoiding cultivars which are known alternate bearers or managing the environment and optimising cultural practices like:

Pruning
In mango growing, the most critical pruning is the frame formation or formative pruning to produce a spreading framework or canopy which forms the fruit bearing surface (dense canopy).

In the first year, when the trees have grown to over 1m above the ground, trim at 0.90-1.0m from ground to encourage side branches.

In year two, leave four to five well-spread branches to be future scaffolds on which the bearing surface will develop. Any laterals below this head or graft union should be pruned off.

Further pruning is not required other than normal removal of dead, diseased, broken wood or parasitic plants. Mango requires dense foliage, which is important in fruit development.

Fertilising
The nutrient requirements of mango trees are dependent on the stage of growth. Fertilisers are recommended after the establishment of a root system (about three to six months after planting).

Mango trees require a good supply of nutrients during the active growth stage until after about four years when they start fruit production and, thereafter, more nutrients are required, especially during flowering and fruit formation.

Excess nitrogen fertilisation in initial stages injures mango roots.

The following general nutrient supply guidelines are suggested but a soil, tissue analysis report or both should be best indicators for mineral element supplementation.

Nitrogen (N):

• Year 1: 50 to 100g Calcium Ammonium Nitrate (CAN) per tree per year.

• Year 2: 200 to 200g Calcium Ammonium Nitrate (CAN) per tree, per year.

• Year 3: 150 to 300g Calcium Ammonium Nitrate (CAN) per tree, per year.

In subsequent years, apply 200 to 400g CAN per tree, per year depending on the crop potential.

Apply rates in two to four splits to avoid losses due to leaching or scorching of roots.

Phosphorus (P) and Potassium (K) general fertilisation based on tree age in g/tree/year (in absence of leaf and soil analyses)

Prof Joseph Wolukau, is horticulture expert, Egerton University

 
(Editor: This response continues next week)