Becoming the conker champion of the world could be tougher than usual this year, because of a lack of conkers.
Two diseases are damaging the horse chestnut trees that conkers grow on, leaving world championship organisers struggling to find big enough conkers.
One disease is damaging leaves, which is where trees get their energy from, while another damages the bark.
Around 500 people are expected to take part in the championship on 12 October, in Ashton in Northants.
None of the competitors bring their own conkers - all 5,000 are supplied by the organisers.
A horse chestnut tree and a conker
They say that it's been hard to track down enough of the right size this year, and they were expecting them to be extra big this year because of all the wet weather this summer.
The leaves are being destroyed by a moth, which leaves its eggs inside them, and when the eggs hatch the larvae munch on the leaves for food.
That makes them turn brown earlier than normal, and means they can't supply the tree with as much energy as they should.
The other problem is a disease called "bleeding canker" and in very bad cases can kill horse chestnut trees.
However, there are still hundreds of thousands of horse chestnut trees in Britain, so there should be plenty of conkers for you to get cracking with for a number of years yet.