If you are a gardener, you will have realised that disease is multifaceted and only in a few cases can it be attributed to a single cause.
Looking closely is the best way to discover the complex ways in which disease acts in your garden. These include overcrowding, nutrition levels, pathogens, stress, chemical use, mineral deficiencies, temperature and vector transmission.
Holistic gardeners always begin with soil, striving to build nutrient rich soil, containing plenty of humus and a wide range of the “bugs” that make a healthy soil food web. This is the basis of healthy, disease-resistant plants.
The next focus is growing plants in season, as many are temperature dependent and get stressed in conditions that are too cold or hot, especially seedlings. Water stress (caused by too much, or too little water) can also lead to disease. Wilting is a sign of water stress, as plants shut down photosynthesis.
The importance of disease transmission via insects is often underestimated. Many insects transmit bacterial and fungal spores passively by feeding in, or walking through, an infected plant area. Commonly, they are insects that have piercing, sucking mouthparts such as aphids, whiteflies, thrips and planthoppers. However, mites, nematodes, and fungi can also transmit plant viruses.
Without those vectors, some diseases would not be able to spread among your plants.
Bacteria can survive in plant debris and infected plant roots, so remember good hygiene is just as important in the garden as it is in our homes!
Everyone needs their own space, and plants are no different. Lack of air space in overcrowded growing conditions leads to more pests, lack of space for the plants to spread their roots, and competition for nutrients. Poor air circulation can increase fungal diseases, such as powdery mildew.
Interestingly, highly fertilised plants become more attractive to pests as the high nitrogen levels can decrease resistance to attack. Synthetic pesticides disrupt the complex web of life in your soils, impacting soil fertility.
Natural pest control
• Gather supplies such as fish frames, seaweed, nettles, comfrey and manure to make compost and liquid manure.
• Remember crop rotation when planting. • Increase insect diversity by planting a beneficial insect garden.
• Pests use smell, so interplant to confuse the scents. • Green shield beetles are a major pest, so check for them every day. Newly hatched ones often hide in calendula seed heads. • Plant beetroot, beans, pumpkin, sunflowers, squash, carrots, and potatoes directly in the garden now.
• Plant tomato, cucumber, zucchini and eggplant seeds in seed sowing mix and keep them warm at night.
• Use row covers and barriers, as well as netting to keep insects off young plants.
• Encourage birds like silver eyes (wax/white eyes or tauhou), finches, blackbirds and thrushes for insect
and snail control.
• Find a source of grass clippings and dry them for use as mulch.