Before spraying, always read and follow label directions.
A copper spray before bud burst is beneficial for preventing a variety of diseases, but not essential if the Autumn copper or Lime Sulphur spray has been done. Check product labels for ratios.
Black Cherry Aphid Prevention
The Black Cherry Aphid can be a big problem on cherry trees. The aphids curl and kill the leaves – particularly the tips of new growth. The aphids secrete honey dew which attracts wasps and the black sticky residue will cover ripening cherries. A prevention spray is strongly advised - especially if you had a problem the previous season.
Spray in the last few days of August or first few days of September, (Otago climate) just as the little scales on the dormant buds start to crack open (about 2 weeks before blossom). At this time most of the aphid eggs have hatched and the young insects are vulnerable - with no leaves to hide in.
For 5 Litres of spray: Mix 2% mineral oil (eg. Yates Conqueror Oil) at 100ml/5L water, and add 25ml Pyrethrum.
Avoid spraying when bees are active, Pyrethrum is highly toxic to bees – best to spray at dusk. It will kill the hatched eggs of pests and the mineral oil will smother the unhatched ones. For 2 small trees you would probably only need about 2L of spray.
Check the leaves mid September for aphids and then every couple of weeks. Once they curl the leaves they are difficult to control. This spray is beneficial at the same time on peaches, nectarines and plums.
Brown Rot Prevention
Brown Rot can ruin your crop. For prevention, spray a fungicide into blossoms at blossom time if the weather is very cold and wet as that is when the problem begins. Blossom time is normally around Sep 20th (Oamaru climate) for the Lapins variety. Stella blossoms around 10 days later.
Once trees are in leaf, you can still spray Lime Sulphur at a weak ratio of 1:200. (Eg: One teaspoon (5 ml) lime sulphur to 1 litre of water).
A spray every two months will help to deter a variety of chewing and sucking pests such as Leaf Roller Caterpillars, mites, thrips, earwigs and cherry slug. It is also a fungicide, so can help with fungal diseases such as brown rot, or powdery mildew.
Brown Rot Control
Spray a fungicide until dripping, one or two times before harvest if you are seeing brown rot - especially amongst tight clusters of fruit. Spores spread very quickly so remove all affected fruit from on and under trees. Lime Sulphur can be used as a prevention from petal fall through to 2-3 weeks before harvest. (5ml Lime Sulphur per litre of water.)
Black Cherry Aphid Control
Black Cherry Aphids can start to appear mid- late October on the tips of new leaf growth. Healthy cherry leaves should not curl. Look on the undersides of any curling leaves. This is where black aphids cluster. If not controlled they can become a big problem. They tightly curl and blacken all the leaves on the tree. Once the leaves curl it is impossible to get spray where it’s needed. Remove and destroy affected leaves and spray all over the tree, especially the undersides of leaves with garlic spray or pyrethrum. Do this at dusk as bees often feed on the red nectar glands at the base of leaves and wet pyrethrum will kill them. Check again every few days, spot spraying as needed.
These foul smelling black slugs sometimes appear on the upper side of leaves in late January, and skeletonise leaves as they eat them. They can be removed and destroyed easily. If in large numbers you can spot spray with an insecticide such as pyrethrum (do not spray Pyrethrum when bees are present). Some people just leave them and they disappear when autumn comes.
This is a great tool year round for pests – however avoid using during blossom. Can be used at 1% strength mixed with water in Spring, Summer and Autumn and up to 4% in Winter. It has a fungicide action and kills insect eggs, larvae, nymphs and adults through suffocation – must have direct contact. Will also kill scale, aphids and thrips. Avoid spraying when trees are thirsty and only spray when temperature is between 4 and 24 degrees celcius. If the residue dries too fast it can burn the leaves.
Cherry trees benefit from a foliar feed mid – late February after the fruit harvest. Spray a seaweed or fish emulsion over the leaves until dripping. This will be absorbed and provide nutrient stores for the following Spring’s blossom and early shoots.
After the leaves have fallen, you can spray Copper to help control a variety of diseases. But be aware that copper build-up in the soil is harmful to beneficial soil bacteria, fungi and earthworms. Some people opt to use only Lime Sulphur dormant sprays and avoid copper.
Spray when trees are dormant Mix at a percentage of 3-4 % Eg. 100 ml of Lime Sulphur to 3 litres of water). This is a general clean-up spray. It is both a fungicide and insecticide, and helps control overwintering pests which can nibble spring buds.
© Evergrow Orchard (2017)