maximum of two to three minutes using the irrigation system. Rain should not fall for 24 hours after application - I had a thunderstorm and 6mm of rain after just eight hours and still the product worked.
DES
never seen a sample with such a huge
Kate had
population of this pest!
The spiral nematodes can reproduce again within 10 to 30 days, so a second treatment was applied at 80L/Ha in August 2007. Following consultation with Colin a third treatment was applied at 40L/Ha in September to try and eliminate as many of the nematodes as possible going into the winter. A hard winter will not kill the nematodes and a mild one may allow the pest to reproduce. There is an ongoing debate that Dollar Spot disease is the cause of the initial grass decline and that the nematodes come in afterwards as a secondary problem. But I believe that the nematodes come first for the following reasons: Firstly, Kate found no fungal pathogens in any of my soil samples. Following the initial treatment with Biomass-Sugar we stopped the nematodes and there has been no further turf damage seen since. No fungicide was sprayed yet, if it had been dollar spot, the disease would have continued to infect the grass plants, something which stopped following the sugar treatment. Even more evidence that it was nematodes is that, following dollar spot attacks on the STRI trial plots, they could not get seed to germinate in the scars until the following spring. Professor Joe Vargas says that it is due to staling compounds left by the dollar spot. These compounds leave the rootzone stale. I have successfully had germination twice in the scars with fescue, therefore, there cannot have been any of these staling compounds in the rootzone, which suggests that it cannot have had dollar spot.
The unknown question is what is this staling compound left by the dollar spot and why should it just disappear in the springtime? Recently a colleague at a nearby course saw his fescue and velvet bent greens start to decline. Kate tested the rootzone and their problem was identified as Sheath Nematodes and not spiral. The damage
threshold is 80 per 100ml of rootzone and they had 250.
It appears that nematodes are going to continue being a problem to all turf growers as long as the climate stays as it is, wet and warm.
Nematodes are non-selective in the grass species that they attack. Kate sees most attacks in the UK on Poa annua and Colin, in Ireland, on Fescue and Bent, but he also sees a lot of damage to rye grass on football pitches.
I have to admit that I went through a very difficult period with the nematodes but, thanks to great help and support from Dr Kate Entwistle, Dr Colin Fleming, Mark Hunt and Roland A Van Stein, I am now a wiser man and know what to look out for in 2008. I also thank Biomass- Sugar, which is available
from Barenbrug, for saving my greens in 2007.
The 17th green been attacked by the spiral nematodes
nematodes which caused the scarring and not dollar spot as the seed would not have germinated
Colin Fleming’s findings
Like Dr Kate Entwistle, I have seen a huge increase in problems caused by spiral nematodes (Helicotylenchus). From the samples I have examined, the key points I would make are:
• Spiral nematodes are now the most common nematode pest we see in advisory samples
• High levels of these nematodes are associated with shallow stunted rooting and severe root damage (the root corticals cells are shearing off the root)
• I have carried out inoculation experiments with spiral nematodes and duplicated the symptoms in pots
• The worst symptoms I have seen have been in bent/fescue/Poa greens with the bents and fescues showing most damage
The photo above shows spiral nematode damage in a bent/fescue/Poa green. Interestingly, this course had 12 perfect greens and 6 showing this type of damage. The club were blaming the greenkeeper (they even suspected he had made a mistake in spraying the greens). We showed them that there was a perfect correlation between the damage and levels of spirals in the green. I have not checked for the presence of the dollar spot organism but, from what I can gather, in most cases the symptoms have not responded to fungicide treatment. I know that since Kate and Mark Hunt first highlighted the root knot nematode problem, there are still individuals in the industry who have not accepted that nematodes can be a significant problem in north western Europe. Ten years ago I would probably have held this view, but the evidence has made me change my mind. Interestingly, in Ireland this year, we have had the first case ever of root knot nematode (Meloidogyne minor) damage in potatoes (causing 70% yield loss) and extensive root knot nematode damage to cereals. The agricultural industry fully accept
nematodes as the cause of these problems and suspects climate change as the key factor in the emergence of this problem. During the last year we have identified two new nematode pests causing severe damage to turf and, unless the climate starts to revert to its ‘norm’, I can only expect this pattern to continue.
Dr Colin C. Fleming Applied Plant Science Agri-Food and Biosciences Institute Email:
colin.fleming@afbini.gov.uk
The 17th green following overseeding twice with fescue proving that it was
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