Deter your white Cabbage butterflies with white plastic replicas
Deter your white Cabbage butterflies with white plastic replicas
Rust on a silver beet leaf
Rust on a silver beet leaf

The Pollyanna view of Pest and Diseases!

Posted 11 Nov 2014

Pests are not always pests and diseases do not always warrant a remedy, just ask Pollyanna. Practice her ‘Glad game’ and you will soon be focusing on the benefits that stem sucking, leaf chewing, pest, fungal and bacterial organisms bring to your garden.

An ideal control technique is to aim for a balanced population of all bugs through the maintenance of diversity. Companion planting is one way of promoting bug diversity throughout the seasons as it provides flowering, fruiting and vegetative options maximising the range of available habitat (homes) and food types to bugs of all genre. It also uses disguise and deception to mask the presence of our more favorable vegetables!

There is no doubt that fleshy spring growth coupled with moisture and warm temperatures encourage explosive bug populations but consider your fruit and vegetable damage threshold (some might call it sharing). How many marks can you tolerate in your apples? Is the life of your tree at risk? Does it matter if one of your cauliflower plants succumbs to mildew while the others thrive? What is your pest/disease tolerance threshold?

Some ways of swinging toward diversity…..
Healthy plants have a greater tolerance to pest and disease attack. Ensure the soil is as the species requires by observing drainage, water retention and mulch thickness. Match your care, cultivation and crop rotation habits to their needs. Plants grown outside of their preferred climate zone will become stressed more readily. It may be prudent to consider replacing these with more climate suitable species.

In Port Campbell the Cabbage White Butterflies have begun to emerge, targeting all Brassicas (broccoli, cauliflower etc.) as their egg laying host. The caterpillars are voracious feeders. Try placing domes of bird wire over plants as the butterflies will not enter for fear of damaging their wings. Cutting butterfly silhouettes from ice cream container lids, piercing them with a stick and placing them amongst your Brassicas is also a deterrent.

Cherry slugs are rapid leaf miners which attack not only cherries but also apple, pear and Nashi trees. To decrease the slug population, choose a windy day to scatter fine wood ash over the tree foliage. Ash contact desiccates the slug without harming the tree.

Large pests like possums and rosellas often take a liking to rose buds and seedlings. Their shredding, plucking and beheading seems revengeful but I suspect that it is more aligned to entertainment. In these instances try applying a triage of remedies. Firstly put in place an obstacle deterrent, for example covers made from bird wire, dangle old CD’s, string up fishing line or tie your dog close by. Secondly offer something the pest finds attractive this may be a pile of surplus shooting potatoes or apple peelings mixed with sultanas or stale bread and thirdly make the plant being targeted taste less than appealing by spraying or painting a mix of cooking oil, pepper, curry and chilli powder onto the plant or soil surface. The application should not harm your plant and because it is not rain fast more than one application may be warranted. As in the crime movies, live the life of your enemy and design each strategy with utmost consideration of the pest in question. Reapply each strategy as required to break the pest’s habit and don’t forget to wear your, ‘I’m committed’ face.

As rainfall decreases and the weather warms plants that have grown rapidly such as corn, and silver beet can suffer from rust while melons and zucchini can suffer from mildew. Rust is typically small orange coloured spots on either upper or lower leaf surfaces that when rubbed will colour your fingers. Mildews are characterised by patches (often circular) of a white powdery film also located on either leaf surface. An effective cure-all is to mix 1/3 milk with 2/3 water and spray over the infected area. The calcium from the milk helps repair the plant’s cuticle layer. This remedy is also an effective barrier to sap sucking pests such as aphids and red spider mite.

Late Winter Pruning Summer gardening's mixing pot