Q:  Ken we need some expert advice on a rhubarb plot that we have taken over on our allotment.  Last weekend we were going to split our rhubarb but found it to be rotten.  We went and purchased some new rhubarb plants but on closer inspection of the old rhubarb we appear to have white chafer grubs.  I can see we can treat them organically with nematodes but this is the wrong time of year to use.   Do you have any other suggestions or can we go ahead and plant our rhubarb and treat later on in the year.  Many thanks, Katie.

A: We have to agree with you that the only sensible method of eradicating Chafer Grub is the use of Nemotodes.  Some people lay black polythene or hessian on the affected ground which will often draw the Chafer Grubs to the surface, and then pulling the material away will allow birds to enjoy an early morning snack.  The other area of the garden that often suffers with Chafer Grub and Leatherjackets is of course the lawn, for which there is a chemical cure available.  This product called Provado Lawn Grub Killer sadly has not got clearance for use on other areas of the garden particularly food crops.  I have in the past lightly forked through ground and literally pulled them out as I see them.  Sorry not to be more help.