Diseases are caused by small micro-organisms, which we cannot see with our naked eyes. Just as animals fall sick, plants fall sick and even die too. Diseases are usually rampant in plantations which full of weeds, are un-mulched, and unprunned, and are normally spread by planting infected suckers from another garden. A good seed is the key to a successful banana plantation. Thus, by using tissue culture plantlets, you are sure you are starting with disease-free seedlings.
The most common and most damaging disease today is the banana bacterial wilt (BBW), which is currently Uganda’s number one constraint to banana production. It can totally destroy a plantation within a few months.
The disease was first reported in Mukono in 2001 and has now spread to the whole country. It is characterised by premature scorching and death of leaves, which turn yellow when they are hanging on the plant, and premature ripening of fruits before the banana is ready. When you cut the ripe premature fruits, the inside pulp is rotten and dark. When you cut the stem, smelly milky stuff oozes out of the stem, and it is referred to as bacterial ooze.
It is only bacterial diseases that can produce such. To address this problem, manage your plantation well, remove male buds on time, do not plant suckers from unknown sources, and most preferably, plant disease-free tissue culture seedlings.
The development of tissue culture techniques is the insurance banana farmers and those intending to start banana farming enterprises now have against BBW, as you are sure that even after you have lost your plantation, you can still replant a new plantation using the tissue culture, disease-free planting materials. The good news is that scientists have proved that BBW does not stay in the soil for more than six months.
If your plantation is destroyed, remove all the stumps, and use the field for other crops or leave under fallow for at least one year, and then procure tissue culture bananas and replant your field.
You will be assured of cleaner more vigorous and better banana plantation than the one BBW destroyed.
Most importantly, if you are engaged in commercial banana farming, be vigilant and engage your neighbours to ensure that their plantations are also free of diseases especially that they get to sensitise about BBW, its spread and measures to control its spread.
Make sure that they remove male buds using forked stick, and that they remove, chop and bury any diseased plants as soon as they are cited. Have a village meeting to discuss how to manage the disease together.
This is the very strategy farmers in some districts in western Uganda such as Isingiro have employed with support of district by-laws to curb the spread of the disease.
The other disease is the fusarium wilt disease, also known as Panama disease, which is soil borne and currently affects dessert bananas such as bogoya, sukali ndizi, kisubi and kayinja. It is a very destructive disease and can lead to up to 100 per cent losses. Symptoms include yellowing of leaves, or collapse of the petiole while the leaf is still green. All leaves eventually collapse where the petiole joins the pseudostem and dies.
Means of transmission
Sometimes, the leaf sheaths loosen and later, the pseudostem may split. After this the pseudotem remains with the dead leaves hanging round it. Normally, the attacked plant fails to flower, but if it does, the bunch fails to develop and fill up. The bananas are infected through roots or by use of infested tools to cut the corms of non-infested plants.
It does not seem to be transmitted through cutting above-ground stems or leaves because the spores have to first establish in the soil for the infection to take place. Thus the major means of transmission of the disease is through planting or infected suckers from one garden to another.
Control can be affected through quarantine, and planting non-infected tissue culture seedlings in non-infested soils. Implements and movement from infested to clean fields should be carefully observed and restricted. Once a mat is attacked, it should be completely destroyed by chopping the plant and burning it. We have looked at two major diseases—banana bacterial wilt disease and fusarium wilt— though there are more than just these two diseases that affect bananas.
In all cases, however, the major means of spreading these diseases from one garden to another is by planting infected suckers unknowingly. The use of disease-free tissue culture seedlings are the surest and modern way of planting a healthy, disease-free plantation for maximisation of returns.
Thus, make it a point this season to start using tissue culture banana seedlings and you confirm the difference, it will make to your enterprise. In our remaining articles, we shall look at pests of bananas, banana varieties in Uganda, and finally cost-benefit analysis of a banana venture.
Fighting the banana wilt
Make sure you maintain your banana plantation very well using the same methods we have discussed in these series.
Do not allow anybody to cut any part of the plant from your garden using their tools such as pangas and knives. Be the one to provide the tools, and make sure your tools are always sterilised either by passing them over a fire or clean using JIK.
Even in your own garden, when you see a suspicious plant, do not cut it and then use the same panga on another plant or stool.
It is advisable that a plant with symptoms of the disease must be uprooted, chopped and buried. The tools used must be cleaned in JIK or passed over a fire to sterilise them.
Remove the male buds from the plants as soon as the bunches finish forming, as the insects that visit them are agents of this dangerous disease.
The writer is chief executive officer, NSIGOTECH Tissue Culture Laboratory.