Summer pests
We’re well into summer now, and hopefully you’re harvesting plenty of yummy summer crops. If you’re like me then you’ll rely on good compost and a bit of TLC to keep the crops growing well. But sometimes they’ll succumb to some pest or disease that we hadn’t counted on. Here’s a few of the common ones (not mentioned previously) with some tips for dealing with them.
Greasy cutworm: A light-brown-coloured moth caterpillar (about 40mm long) that feeds on young stems of seedlings at night, eg lettuces, beetroot and corn. Tilling the soil surface with a niwashi or hoe disturbs them. If found then squashing is best. Cultivating the garden well reduces their habitat. Encouraging plant diversity will hopefully bring beneficials like brown soldier bug and parasitic wasps and flies.
Tomato fruitworm or corn earworm is a moth caterpillar that eats fruits (eg tomatoes, corn), buds and flowers. Similar in size to cutworm, the pupa (golden brown capsule) can be destroyed by soil cultivation. Spray Bt (Bascillus thuringiensis) or Dipel to control the caterpillar. Again encouraging parasites and predators with flowering plants helps limit them, too.
Wireworm: The larvae of the click beetle shelter in the soil and attack roots, tubers (eg potatoes), stem bases and seeds. As with cutworm attack, seedlings just wilt and die and seeds fail to germinate. Difficult to control, but the most effective method is to cultivate the soil before planting (especially if has been in pasture/lawn).
Vegetable weevil: Obvious by their long snouts, these beetles (5-10mm long) and their larvae (10mm pale grubs) attack many vegetable leaves (eg brassicas, lettuce) and roots/tubers (carrots, potatoes). Control larvae by soil tilling before planting. Practice crop rotation. Remove all plant residues, then hot compost. With potatoes and kumara, remove infected tubers and destroy. Also remove beetles found on leaves, as otherwise only strong insecticides will work.
Carrot rust fly: Adult flies lay eggs on top of carrots and parsnips in particular, and larvae burrow into roots, leaving holes. Control by keeping these crops apart. Plant tall crops between them, and aromatics like onions. Rotate crops. Remove thinnings and mound soil up over root shoulders. Mulch after thinning with fresh grass clippings.
Caterpillars—green looper, cabbage white butterfly and diamondback moth: These caterpillars are green and 40mm, 25mm and 9mm long respectively. They attack many vegetable crops (eg brassicas), eating chunks out of leaves. Hand removal or spraying with Bt are the most effective control measures. Encouraging beneficials helps heaps.
Fruit care
Water fruits in dry spots and keep all fruits mulched.
Support really fruit-laden branches so they don’t break.
Summer prune after fruiting: when sunny prune out water shoots growing low on trunk or in centre of fruit trees, especially stonefruit. Prune out old canes of berryfruit.
Watch for silver leaf, prune out affected branches and treat cuts with trichoderma or insert bio dowels in trunks.
Tip figs once fruit buds present to encourage better fruiting.
Cover berryfruits with netting to stop the birds.
Change pheromone traps to prevent codlin and leafroller moth damage.
Put bands of corrugated cardboard around fruit tree trunks. Remove and burn every two weeks to limit moth caterpillars. Barrier paste on band helps trap them.
Strawberries need fortnightly liquid fertilising with comfrey. Mulch with pine needles or wood shavings.
Spray fruits with liquid seaweed as a tonic. Spray Bt vs moth larvae fruit damage on berryfruit. Spray garlic and pyrethrum vs pear slug damage on pipfruit.
Also spray citrus with all purpose oil for scale insect and aphid (or use garlic and pyrethrum).
Prune citrus when harvesting.
Prune grapes.
Herb Care
Keep harvesting to stall flowering. Dry excess.
Sow basil, coriander and dill direct every fortnight.
Plant parsley.
Weed and mulch.
Vegetable care
Harvest garlic, onions and shallots when tops flop. Lift and dry in sun. Clean, plait and hang.
Keep weeding and make lots of compost.
Plant winter brassicas and celery into a fertile bed. Cover to protect from pests (netting or shade cloth).
Plant leeks using a dibber and just water in.
Last chance to sow parsnip and other roots now.
Sow salads every two weeks.
Earth up potatoes and yams. Harvest potatoes.
Liquid fertilise in the morning once a week.
Delateral tomatoes and cucumbers and remove lower leaves as they grow.
Watch out for pests and diseases, especially aphids on young seedlings, and spray with natural garlic and pyrethrum. Spray Bt onto brassicas vs caterpillars.
Sow and plant lots of flowers to attract beneficial insects.
Hothouse: Liquid fertilise weekly. Use yellow sticky cards/bands for whitefly. Keep well ventilated. Spray with garlic and pyrethrum if plants get aphid infestations.
For transplanting: Leafy greens (summer spinach, silverbeet/chard, lettuce, endive and cabbages)(best 30th Jan). Broccoli, cauliflower (best 31 Jan–1 Feb). Flowers, eg sweet pea.
Sow direct: Mesclun salad, radish, spring onions, carrot, beetroot, parsnip, French beans, kohlrabi, swede and turnip (best 3-5 Feb). Flowers, eg hollyhocks.
Plant: Salad greens, silverbeet/chard, spinach, celery, kale, cabbages and leeks (best 10–23 Feb). Flowers, eg self-seeded pansy.
General garden care
Collect water in drums.
Prune trees and shrubs after flowering, including roses.
Collect seaweed/seagrass.
Make lots of compost. Turn heaps.
Make comfrey liquid fertiliser: cut, fill drum, add water. Wait a month before use.
Mulch citrus and ornamentals with grass clippings. Mulch-mow lawn.
Sol Morgan, GroWise Consultancy
