Yam Field and Storage Diseases

[MustyJ]

Yams are one of Nigeria’s stable food crops. It is also in demand for export. Nigeria has a unique advantage of being a world leader in the production of yams. Nigeria produces 22 million tonnes of the worlds production of 30 million tonnes. Unfortunately, 25% of the production are lost to diseases and pest while 50% or more are lost to storage failures. The result? Poor income to farmers, huge seasonal variation in prices, lost export opportunities, high produce costs.

Today, I shall highlight a couple of diseases that yam farmers need to be wary of, at lease to help recover some of the 25% and 50% loses for plant and storage loses respectively.

Field Diseases

(i Anthracnose disease of yam this is caused by a fungus called Colletotrichum gloeosporioides This diseases shows up at the seedling stage. The yam cultivers show signs of dark brown or black spots on the leaves and stems of the young plant. The leaves then whether and die. They have a scotched appearance and hence the disease is sometimes called ‘name 'scorch' disease

(ii) Yam Mosaic Virus Disease (YMV). This is caused by an aphid which transmits a potyvirus
that infects manifesting as vein banding, curling of the plant, shedding of leaves. (YMV) is very serious and can cause huge losses in yams farms. Spotting this symptoms should raise an alarm in any yam farmer

(iii) Water yam virus disease called Dioscorea alata virus. This disease causes the plant vein to bend, flecks, circular spots and leave falls. This disease is common

Storage Diseases

(i) Dry rot: This happens when tubers are infected with Penicilium oxalicum and P. cyclopium. The yam tubers turn brown, become hard and dry but still maintain their shape. Sometimes, the tubers may be infected with S. marcescens and becaome covered with a greenish substance from the fungus. Also, tubers may turn brown with a tinge of yellowish margin. In some cases infection by a particular strain may cause the tubers to first turn grey and subsequently black and fall apart

(ii) Soft rot: Th infected yam tissue turns brown and soft/wet. I have experienced this one 3 years ago when my yams literally rotted away and smelled badly.

(iii)Wet rot : in this scenario the yams are infected with a bacteria Erwinia carotovora pv
carotovora white fluid oozes out of the yam tuber.

What measures to take

Nothing beats speaking with the experts one on one for help. However, the following might help;

(a) Consider crop rotation, fallowing and planting of
healthy materials and the destruction of infected crop

(b) Consider testing soils for the presence of pathogens and then consider planting other crops if their presence are confirmed.

(c) Consider using nematicides such as carbofuran granular or Fernasan D at the planting stage

(d) Consider planting of yam cultivers from certain sources to eliminate or reduce the risks of nematodes. Careful selection of cultiver will hep in this regard.

(e) During storage, try to minimise physical damage to the tubers

(f) Consider treating the yam tubers with Benlate and Captan or insecticide dust (Actellic 2% Dust; ai=pirimiphos-methyl) to reduce fungal yam rot

(g) Insect attacks can be controlled by application of diazinon and carbofuran. While treatments of the yam tubers with

(f) Consider storing yam produce in semi processed form such as yam chips and dried cubes for longer shelf life



What disease isssues have you encountered in your experience? How did you tackle it?

[Achi]

I once bought a significant quantity of yams for resale. I tried to store it locally as advised. I prepared a small ground silo as advised and stored the yams for about 3 months. To my shock and horror, they were infected with soft rot as described above. I was able to salvage only about 40% of my stock. I have never tried that again.

It is nice to know there are chemicals to use against these fungi. But one needs to be sure how much length of time before the tubers will be safe to eat.

[bonama]

I know of a storage system where yam is tied by ropes and suspended. How good is that against rot?

[MustyJ]

You mean these one?

download.jpg (13.58 KiB) Viewed 12971 times

download.jpg (13.58 KiB) Viewed 12971 times

[BeJimmiepreby]

You are a sweetie and I appreciate your time and trouble helping me

xoxoxo

Last question of the day...... How do all f you post you tube vidoes that are small but watchable? so neat