Winter pests and diseases
The cool winter weather we’re having can be a blessing, as it limits populations of pests and diseases. It is also a good time to implement preventative practices, like pruning away infested wood, clearing shrubs and trees to improve airflow, and feeding the soil with healthy compost. There are some pests and diseases that tend to persist and need more care to bring into check. Here are some tips on how to treat them.
Black citrus aphid and woolly apple aphid: Easy to identify, these aphids can be minimised by encouraging tiny beneficial wasps, ladybirds, lacewings and hoverflies. Plant perennial flowers like everlasting daisy. Spray with neem oil, garlic and pyrethrum or homemade garlic spray.
Scale: Common on citrus, these tiny shield pests can be minimised by attracting beneficial insects as above. Spray several times with all-purpose mineral oil available from garden centres.
Lemon tree borer: Also common in citrus, these insects cause yellowing and then dieback, potentially killing the entire bush. They’re best controlled by pruning out affected branches and burning during winter. Check shelterbelts for infestations and prune. Spear with thin wire down each hole, and/or inject with kerosene or meths.
Downy mildew: This common fungal disease of brassicas, leeks, spinach, lettuces and peas forms greyish-white patches on leaf undersides. Remove affected leaves straight away. Improve airflow by avoiding close planting, and keep well weeded. Spray with garlic or bicarbonate of soda solutions.
Rust: A common fungal disease of silverbeet, celery, beetroot, broad beans, garlic and leeks, identified by brownish-orange spots on leaves. Remove affected leaves and mulch with seaweed/seagrass. Rotate crops to avoid infection later on. Liquid feed under plants with comfrey juice.
Fruit care:
· Harvest persimmons, kiwifruit and tamarillos.
· Plant fruit trees, eg black boy peach. Plant in sizeable holes with compost and ensure good drainage. Firm well and stake.
· Re/plant strawberry patch.
· Spray stonefruit and pipfruit with cutonic copper vs bacterial diseases once leaves fall, or liquid seaweed as a tonic.
· Prune fruit trees; avoid big cuts in winter. Burn diseased prunings.
· Clear grass and other weeds away from fruits and re mulch with woody compost.
· Plant perennial herbs and flowers around orchard to attract beneficial insects.
· Apply fertilisers to fruits, eg rock phosphate, lime, boron and wood ash.
Herb Care:
· Place cuttings of rosemary, sage and other semi-woody herbs in coarse sand under cover.
Vegetable Care:
· Protect sensitive crops from frost with a cloche of mikroclima or plastic.
· Prepare ground for garlic, onions and shallots.
· Plant winter crops now, eg garlic, cabbage, broad beans and corn salad. Plant winter/spring salads under cover or in containers in a warm spot.
· Liquid fertilise in the morning once a week. Avoid using cold well water.
· Weed and mulch (eg seagrass around broad beans).
· Stay observant for pests and diseases. Check under rocks or wood edging for slugs and snails.
· Tend asparagus beds with lots of compost and straw.
· Hothouse: Plant salads.
· Check out seed catalogues to get inspired for spring.
· Plan garden cropping and rotation in readiness for spring.
Sow for transplanting: Leafy greens (winter spinach, lettuce, endive, cabbages, spinach beet, Chinese cabbage and onions). Flowers, eg calendula.
Sow direct: radish, spring onions, salads and spinach. Broad beans (27th-28th June). Flowers, eg alyssum.
Plant: 21st June. Garlic and shallots (29th – 30th June). Salad greens, spinach, cabbages, spinach beet. Flowers, eg divided perennials.
General Garden Care:
· Turn composts. Collect leaves into compost ring.
· Prune back flowering plants and hedges. Shred prunings.
· Remove overcrowded trees and shrubs.
· Prune trees for greater sun on edible garden.
· Wrench trees and shrubs for moving in two/three weeks.
· Transplant perennials.
· Clean and fix garden tools. Make a tub with used cooking oil and sand/sawdust mix to dip tools in after use.
Sol Morgan, GroWise Consultancy. Ph 525 9110.
