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Talking Roots with Darryl Shailes: Infrequent pests and disease causing problems


For most growers it’s been a good potato lifting period, and crops have gone into store in good condition. Yields have been better than predicted and some. 

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Infrequent pests and disease causing problems #talkingroots

Irrigated crops in the East have been yielding as well as anyone can remember. This is not just down to the growing season, but also from the uptake of newer varieties by the packers and processors – it’s great to see some of the pallida-resistant varieties doing so well.

However, as always there are a few issues which can have a serious financial impact, and there have been reports of various problems up and down the country which show up less frequently than the normal roots and pest problems.

One disease which seems to be particularly bad this season which is not seen that often on many farms is violet root rot (VRR). It is probably due to the weather we had in August – pretty wet and mild – which has triggered bad infections in some fields with considerable losses of yield.


Any infection of VRR is a problem, especially in stored crops, as there is the potential for further breakdown of other tubers not originally infected.

Farms which have VRR are generally aware of it, but it can be put to the back of the mind if it has not been a problem for a few years. The only real control is rotation, but we may need to consider whether modern cropping plans really take this into account.


The current rotation models seem to have many carriers of VRR, which may get missed. The obvious ones are potatoes, sugar beet and carrots, but what about other crop types which are grown on the farm, or on the land which has just been rented?

Brassicas are VRR carriers and this will include oilseed rape. Rape was not very prevalent in potato rotations a few years ago, but it is much more common now, and also several of the species used as cover crops such as mustard and fodder radish can also carry the disease.


Lucerne and vetches have also been identified and then a wide range of weed species such as groundsel, wild parsley and thistles have been implicated. So, where there is a history of VRR its rotational management needs consideration.

Another pest which is usually an infrequent problem but has been reported more this year is chafer grub . If your crops have never suffered an attack from them consider yourself lucky – a bad infestation can be devastating – like the worst slug problem you have ever seen. There is not really much you can do about it as they migrate out of woodland and the grass margins of fields.

You can set pheromone traps to let you know when the adult chafer beetles (or May bugs as they are commonly known) are around, but there is no real treatment to apply. The adults can lay their eggs in the soil around the tubers and when they hatch they can quickly cause serious damage in a crop.


There are some varieties which appear to be more susceptible, including Maris Piper, so if you suffer from the problem perhaps try a different variety in the known hotspots.

There have also been a few cases of wireworm appear this year. Trapping for wireworms in the previous year can at least give some idea of the potential issue and then a suitable treatment can be applied, but again this pest can be devastating when it first catches you unawares.


There are some indications non-inversion tillage and grassy stubbles can encourage them, so beware if these feature in the crop rotation. Thankfully these issues are not that frequent.

On a brighter note, the AHDB potato event takes place in November. Everyone in the potato world should be present, so there will be plenty of opportunities to discuss any issues you may have with the various industry experts.


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