Melon Soil Management

Best high-yielding quality crops are grown on well-drained, deep, highly fertile soils.

Melons have a shallow root system and are intolerant of drought and waterlogging. Thus, sandier, lighter textured soils are preferred. On heavier soils, watermelons are more prone to cracking.

In poorly drained or low pH soils, Fusarium spp. and foot rot can be a problem. The use of ridges or beds, that are faster to warm-up, will encourage quicker growth and earlier crop development. Beds will also provide better drainage.

A wide crop rotation is advisable, particularly where nematodes are a problem. In some areas, soil disinfection is carried out to minimize nematode damage and soil diseases. Where this is practiced, rotations can be shortened.

Optimum pH is between 6.0-6.6, but crops are grown in soils with a very wide range of pHs. When pH drops below 5.5, magnesium and molybdenum availability drops and above 6.5, zinc, manganese and iron become deficient.

Soil and Plant Analysis

Soil analysis is used to provide initial baseline information for a fertilizer program – particularly as an indication of potassium and phosphorus needs. It is also used to assess soil pH, and organic matter levels.

Leaf analysis is important to continually monitor the balance between elements and fine-tune a fertilizer program that ensures quality fruit production.Leaf analysis will also confirm visible deficiency symptoms and reveal hidden deficiencies where visual plant symptoms are not yet present.

It is necessary to take into account the sampling method used and the time of sampling when interpreting the data. It is also important to wash leaves before testing as dust, foliar fertilizer sprays and fungicide residues can create artificially high readings.

Crop Protection

Plant breeders are increasingly introducing varieties that are resistant to, or offer partial resistance to, a range of diseases, such as alternaria, stem blight, mildew and damping off as well as aphid-borne mosaic viruses.

Growers can minimize the impact of diseases by using appropriate fungicide programs. Integrated crop management techniques that keep the soil and foliage dry will help minimize outbreaks of diseases such as dampingoff and blight.

Root-knot nematodes are a serious problem, impairing the root system and preventing effective nutrient and soil moisture uptake. Growers need to adopt a sensible rotation or use soil fumigation to reduce pest damage.

Insect pests that include white fly, thrips, cutworms, aphids, caterpillars and cucumber beetles all cause injury to melon plants. Soil or foliar insecticides should be used once local pest thresholds have been reached.

Weed control is essential to reduce competition for moisture and nutrients. This is particularly important at the establishment and early growth stage. Growers most commonly use stale-seedbed techniques removing the weed burden prior to planting or drilling. Later on in the season, the creeping nature of the plant tends to smother and so reduce the weed burden.

Plastic mulches provide excellent weed control over the planted row – the interrow weeds can be sprayed using approved herbicides or pulled by hand. Where no mulch is used, care needs to be taken when using appropriate post-emergence herbicides, as young plants are vulnerable to damage.

Cultivation to remove weeds between rows should be shallow, so as not to disturb the delicate root system of the melon crop.