Citrus trees that are growing in our predominately clay-based soils may develop signs of mineral deficiencies, particularly through the warmer months.
Mineral deficiencies will generally appear as abnormal or mottled colourings on leaves including a yellowing of the general leaf area while veins remain a deeper green colour. Zinc and magnesium deficiencies are the more common forms in citrus trees the home garden, although deficiencies in nitrogen, boron, phosphorous and manganese may also occur in other plants.
Zinc and magnesium are required in appropriate quantities in order for the proper functioning of chlorophyll. Proper root growth, plant nutrition, reproduction and optimum crop growth are all dependent on balanced levels of minerals.
The fastest way in which to rectify deficiencies in citrus trees is through the use of a foliar feed. This involves applying feeds to the leaves of plants so that it is absorbed rapidly into the plant's system.
The use of zinc-coated nails, nailed into the side of a tree, will provide the tree's zinc needs over the coming years.
A foliar feed, as described by Peter Cundall, can be applied to citrus trees as well as leaf vegetables and can be prepared in the following manner.
A 10-litre bucket of water should be almost filled with water. To this should be added; 1/2 cup of fish emulsion, 1 cup of seaweed concentrate, 3 teaspoons of zinc sulphate and 3 teaspoons of Epsom salts (magnesium sulphate). This mixture will supply nitrogen, through the fish emulsion and micro-elements present in the seaweed concentrate.
As this mixture is very concentrated and would cause severe damage to plants if applied in this form, it must be diluted prior to application. One part of the mixture should be added to ten parts of water. In fact, it is important to use the solution at a weaker rather than a stronger concentration.
The solution can then be sprayed over and under the foliage of citrus trees as well as leafy vegetables including cabbage, cauliflower and silver beet., as well as mature zucchinis.
Plants should be thoroughly watered before and after an application of the foliar feed. Late afternoon, during the main growing season is the preferred time. Applications should be made every 3-4 weeks.
Unused concentrate can be stored in child-proof containers, ensuring that it is heavily diluted before application.
Potassium deficiency in plants will become evident as a yellowing of leaves. It can affect the plant's sap flow as well as the formation and flavour of fruit. Potash, which provides potassium in a soluble form, should be mixed at a rate of half a teaspoon in 4 1/2 litres of water. After mixing thoroughly the solution can be applied to the root area of plants.
Geraniums are hardy, reliable plants that usually provide extended periods of flowering. However, without regular maintenance plants can become straggly.
Although geraniums are generally disease-free plants, they can be affected by rust. This is a fungal disease that appears as yellow areas on the upper surface of the leaves. Brown, black or orange markings will be evident on the corresponding undersides of the leaves. Apart from these markings causing an unsightly appearance on the leaves, rust will lead to deformation and withering of the leaves. They will fall off the plant prematurely. Leaves that fall to the ground will then assist in further spreading of the problem.
If left untreated, rust can eventually lead to the plant dying.
Diseased leaves should be removed by hand and then disposed of with the general garbage. Pruning back diseased stems will encourage healthy, new growth. An application of a general fertiliser will soon bring the plant back to a healthy state.
A fungicide will be required for complete treatment of the problem. Garden centres should be consulted for suitable products. Repeated applications may be necessary, depending on seasonal conditions.
A wide variety of vegetables can be planted out now so that they will produce during the later summer and early autumn months.
Dwarf beans that are planted out now will be ready for harvesting from May. Seeds should be sown directly into the garden where they will grow.
Beetroot are easy to grow and can be harvested when the fruits are about the size of golf balls. They will be tasty and tender at this stage.
In order to be able to separate the seeds prior to planting, the seeds can be soaked in water for 24 hours.
Thinning of the young plants is generally required when the seedlings emerge from a seed ball of several seeds.
Carrots are a hardy root vegetable that grows well in deep, cool soil. Seeds, which will take about three weeks to emerge, should be sown directly into the garden bed. Seeds are very fine, so mixing the seeds with radish seeds will assist in determining the sown areas as the radish seeds will germinate quickly.
Onions come in a range of colours and sizes.
Brown onions have a strong and pungent flavour. They usually keep well for storage.
White onions are milder but still flavoursome. They keep fairly well.
Red onions are quite mild, suitable to use raw in salads and sandwiches.