WATERMELON

WATERMELON

Watermelon is the commonly known name for Cucurbita citrullus, a cucurbit native to Central Africa, where one can still find certain species in the wild. Already known in ancient Egypt over 5000 years ago, where it is depicted even in some hieroglyphics, it arrived in Europe around the 12th or 13th century following in the invasions of the Moors. It is a very productive plant that generates fruits that can weigh as much as 20 kilos and its production can surpass 10 kilos per square meter. Watermelons are very rich in water and sugary substances despite having an extremely low nutritional value (only 15-26 Kcal/100 gr.) This means that eating a kilogram of it, one arrives at the energetic value of two hard-boiled eggs. The watermelon is the symbol of summer and, in fact, it is usually produced in the months of July and August. The optimal temperature for its development is around 30 °C. Usually, the watermelon is a trailing plant with lobed leaves and branches covered with thick hair. Varieties are available on the market today that are distinguished by the shape - round or elongated – by the size - large or small (baby watermelons) - the colour of their skin - striped or uniform dark green - the colour of the pulp - red or yellow - and finally for the presence or absence of seeds: normal watermelons or seedless varieties. The watermelon, like the melon, is a monoecious plant, i.e. it contains male and female flowers separately on the same plant. Insect pollinators are extremely important for pollination.

CULTIVATION

The seedlings of 3-4 leaves are used when cultivating this plant, which should be planted near the top of the soil and placed in prose (strip of land between two furrows), with a density of 0.5. to 1 plant per square meter. The planting period must occur early on during spring and summer, when temperatures are sure to exceed at least 15 ° C. To obtain a good production, it is advisable to plant in early May in order to have the fruits from late July to August. Fertilization must take the high productivity of the crop and the high removal of nitrogen and potassium into account. According to the removal of the main nutrients, usually in a relationship of 1:0,4:1,3 (N, P, K), the fertilization will include 2-3 kg /sqm of organic compost, 50g / square meters of Potassium sulphate (never chloride), and 30g / sqm of triple phosphate. During cultivation, but only after fruit set (when the fruitlets are as big as a walnut) those wishing to use a fertilizer of natural origin can add two or three doses of nitrogen in the form of potassium nitrate or guano. The administration of nitrogen, in organic or mineral form, must be done with great care because, if in excess, the plant will tend to produce more leaves than fruit.

ADVERSITIES

Like other cucurbits, watermelon fears the continuous cropping on the same land or on parcels of land that have hosted other cucurbits for several years. This is because during cultivation these soils become enriched with pathogenic fungi such as fusarium and verticillium, which easily attack and penetrate the plant by the roots or the collar. The only sure way to overcome this problem is to resort to the grafted plants of special varieties of pumpkin. The foliage can be attacked by powdery mildew or Pseudoperonospora. To contain these attacks it is opportune to intervene with a preventive care with copper based and sulfuric compounds, repeated every 2-3 weeks. As for insects, aphids are particularly harmful but can easily be fought with natural pyrethroid sprays, taking care to avoid the treatment during bloom. Another option is to intervene by throwing insect predators such as Chrysoperla carnea, the Aphidoletes aphidimyza, the Aphidius colemani, and Harmonia axyridis. A final warning should be given with regard to the attacks of red spider, which can be distinguished by the extremely fine cobweb weaved on the vegetative apex and below the leaves. These can be fought using the predatory mite Phytoseiulus persimilis.

HARVEST

Maturation occurs approximately 120 days after germination and can be seen by noting that the cirrus placed on the node next to the stalk gets dry. Other symptoms of maturation regard the change in the striped watermelon's rind's colour from greenish to yellowish. We may also refer to the sound emitted by percussing on the fruit. If it sounds dark and dull, the fruit is still unripe. On the other hand, once mature, the sound will be crystalline.