Helpful advice on how to stem leafcurl
Any peach or nectarine trees infected by leafcurl disease last spring will be infected again unless preventative sprays are applied now. It’s urgent and fungicides must be applied before the tips of the new leaves appear.
The spray to use involves copper, an effective killer of almost all parasitic fungi. Right now, leafcurl organisms are already clustered around leaf buds waiting for them to open.
This destructive disease loves moisture, especially the soft, stickiness of newly-opened leaf buds. As soon as the protective outer skins of leaf buds crack open in about a week, the leafcurl disease attacks. It is helped by rain which washes in the deadly organisms.
Newly-planted peach and nectarines are particularly vulnerable and many young trees are killed during the first season being too immature to put up much resistance.
Apart from spraying young trees, we
Once leafcurl strikes, no matter how often the trees are sprayed the disease will still continue to devastate
can provide temporary protection by stretching clear plastic film over the branches to keep rain off. Once leaves have fully opened and are no longer sticky with sap, the relatively dry surfaces becomes resistant to leafcurl.
Larger trees are too big to be covered so we use sprays that can cling protectively around vulnerable buds despite normal rainfalls. This is why homemade Bordeaux or the much stronger Burgundy mixes are so valuable. The only reason why these preventative sprays fail to protect is because of poor timing; being applied either too early or far more commonly too late.
Once leafcurl disease has struck, no matter how often the trees are sprayed the disease will still continue to devastate the trees. So get spraying this weekend and spray again when blossom buds swell
and turn pink, always just before leaves appear. If necessary, cut off about 100mm from the tips of each branch because that’s where the first leaves start to open.
Use two 10 litre buckets to make these well-tried fungicides. Half-fill one with cold water and the other with the same amount of warm water. Dissolve 100gram of builders’ lime in the cold water and 100gram of copper sulphate (available at garden centres) in the warm water. Then pour the lime mix into the copper mix and stir.
The result is Bordeaux mixture, which when freshly made is particularly effective. When applying it to branches – right to tips – keep the contents of the bucket agitated, otherwise it will settle and can block spray nozzles.
Burgundy mix is almost the same except that instead of lime, use washing soda (cheaply available as a foot-bath). This mix is not a nozzle blocker, which is why I prefer to use it, but being much stronger than Bordeaux can cause leaf damage.
I also spray quince trees to control fleck, a disease that infects the fruit, first covering quinces with black scabs before the finally rot before ripening.
Plum and apricot trees are also attacked by shot-hole, another fungal disease which causes brown spots to appear on leaves which then open so each leaf is covered with tiny holes.
Spraying with either of these homemade fungicides now can give good control.
Another fungal disease which attacks lemons and to a lesser extent other citrus fruit is citrus scab (pictured, inset). We see it as black, sunken spots in the skins. The infection mainly comes from diseased, rotting fruit lying beneath citruses or infected fruit still hanging. Any branches in contact with the soil due to heavy fruit, also transmit citrus scab.
Skirt pruning to cut off all extra-low branches helps, but all fallen or infected fruit must be removed and taken away – although even scabby fruit can still be used for juice.