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Coffee Leaf Rust Fungus Hemileia vastatrix I am sure, you will have heard about the Coffee Leaf Rust Fungus; a fungal infection of the coffee leaves, which kills the leaf, and could reduce the coffee crop (next season) by up to 50%.
A view across the gully behind my house; a whole plantation with hardly a single leaf left on the coffee bushes.
One of my older coffee bushes, almost completely de-leafed; the ripening berries are still there. Much of the bush is not (as it appears) dead, but will regrow over the next few months. The infection has spread all across the Arabica growing areas of South and Central America, and into the Caribbean Islands. Here in Jamaica, predictions are for a crop loss of between 25 and 50% (depending on whose figures/estimates you believe!). Robusta coffee appears to have a natural immunity to the fungus, and suffers comparatively little damage from it. The only thing that we can be certain of is that the price of Arabica coffee from this region will increase next year. Just cannot see the farmers/growers getting more than a miniscule part of the higher price, it will all end up in the pockets of the processors and dealers: such is the way of things!! Some of the more "fanciful" growers are talking about a near doubling of the price they get next year: they might get a few dollars more, but nothing compared to the price increase for the exported beans. Something "good", amongst all the doom and gloom:-
Thought some of you might like to see a picture of the latest addition to my family, our new puppy: named her Poppy, and she is about 12 weeks old. Found her at the local dog rescue centre, so starved that they did not give her much of a chance of surviving: a few weeks of intensive feeding, love and fuss, and she is doing very well! This particular fungus has been around for many years, and usually only "hits" the odd coffee bush around here: the crop loss is minimal, and comes nowhere near the cost of spraying the coffee plantations. Apparently, due to some unusual climatic conditions (higher than normal temperature and humidity) towards the end of last year, the fungus spread over a wide area; and instead of the usual "minor" infection, we got a really bad one.
A coffee bush that was completely de-leafed, but it is already (in a few weeks) re-growing its leaves: to the right of it, another bush which only had a "medium" infection, and has retained some of the leaves. And just a few feet away is another bush, with not a trace of any infection at all. The first sign of the fungus, is a small spot on the coffee leaf: a small yellow circle of dying leaf, unfortunately, the initial spot looks just like the many other leaf fungal infections, which do very little damage to the coffee leaves, and like the Borer Beetles, have to be accepted as part of the normal way of things. By the time the fungus starts to produce the orange coloured sporangia (on the underside of the leaf) it is almost too late to treat it effectively. We were comparatively lucky, and managed to spot it, early on, and immediately sprayed the whole plantation: with a loss of only around 15% of the bushes, and some partial leaf loss on about another 20%.
The first signs of the leaf rust: yellowing patches, which turn brown in the centre, as the cells of the leaf die, then as the area dries out, it turns grey, and becomes almost translucent.
As the infection progresses, more of the leaf turns brown, as it dies.
Until most of the leaf dies, and it drops off the plant.
The specific sign of Hemilea vastatrix are the orange coloured sporangia which appear on the underside of the leaf.
A bush with one old leaf left on the shoot, the fungicide spraying caught this leaf in time, and killed the fungus: but only a few weeks later and the shoot starts producing new leaves. Towards the top of the picture, at the right edge, you can see the change in the colour of the stem, from darker green, to a lighter green, and then a short brown bit: the flowers will only appear on the old part of the shoot, and this new green part of the shoot, will (or should!) be the place where the flowers grow, next year.
On a nearby shoot, the berries ripening, but the whole of the growth that would bear next years coffee crop; completely dead, and has turned a grey colour, the colour of totally dead, wood. The fungus kills not only the leaves themselves, but part of the fresh "green" shoots that the leaves are growing on, where the coffee flowers for next seasons crop would grow from.
A long shoot, all the mature leaves, gone, but this is quite a young, strong, coffee bush; and the tip of the shoot survived, and only a few weeks later, a new set of leaves is growing, strongly. I have been reading in many articles on the internet, that this fungus will kill all the infected coffee bushes: this is just NOT true: the coffee bush will lose (possibly) all its leaves; and it is only the very "sickly" bushes that will not survive, the bushes that were due for replacement, anyway. We were not expecting such a serious infection, and it caught us out: but as soon as the infection was identified, the coffee was immediately sprayed with a systemic fungicide. To be continued ... Robin Plough, a friend of www.coffee4dummies.com For questions about JBM, mail to: Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript |
Special Report: Coffee Leaf Rust Fungus Part 1
Special Report: Coffee Leaf Rust Fungus Part 1
