Watermelon belongs to war season family crops like squash, cucumber and pumpkin. It can be grown on well drained soil.
Watermelon shape can be round or oval. While the rind color can be dark to light green and with or without strips. Its varieties can be divided into three groups,
Triploid or seedless
Planting and Spacing
Watermelon seed germinates at soil temperature of 68F to 95F and germination is slow below 70F. At 77F soil temperature, seed is germinated in five days. Its seed should be planted one inch deep.
Almost 0.5 to 1 kg seed is required for one acre which depends upon seed size, germination ratio and plant to plant distance.
Two type of flowers are produced in watermelon, male and female. At flowering stage a male flower is produced at every node while a female flower is produced at every seventh node approximately. A flower remains only for one day. Therefore a lot of insects are required for pollination. In average conditions, two to three fruits set on a plant.
Research has shown that on average, a female flower should be visited seven time by inset for proper pollination. Insufficient pollination may result in deformed melons.
Blossom-end rot (BER)
Its physiological or nonparasitic disorder which is related to calcium deficiency or moister stress or both. Its prevention can be made through enough amount of calcium, proper soil pH, and a consistent and better supply of moisture.
Hollow heart (HH) and white heart (WH)
It’s a physiological disorders which is generated by genetics, environment and a number of other nutritional factors. Its prevention can be made by adopting cultivars that have not shown high incidences of HH or WH and the crop should be grown under optimal nutritional and moisture conditions.
It is caused by a seedling disease that involves Phythium spp., Rhizoctonia spp. or Fusarium spp. The prevention can be made by good cultural practices and seed treatment for damping-off of young watermelon seedlings. Most favorable conditions for damping-off are cool, wet weather.
These are small eel-like worms that live in the soil and feed on plant roots. These cause severe damage to this crop in infested soils.
Nematodes damage the root system therefore the plant cannot take up water and nutrients. Also they permit diseases like Fusarium wilt to enter the plant. Serious root-knot injury usually seems as stunted, wilted growth. Before planting the crop, watermelon fields should be analysed for this disease.
Gummy Stem Blight
It is a fungal disease which causes stem canker, crown rot, damping-off, fruit rot and leaf spot in this crop. The leaves become round or irregular with brown color. The affected area on the crown and stem become brown and white with the passage of time. Early attack comes from diseased seeds. Brown to black spots can be observed between the leaf veins of older leaves. This disease spreads from the center of the plant outward.
This is a destructive disease and it can attack on any time in crop. Its symptoms are round to angular reddish brown spots on the oldest leaves which may later dry, turn black and tear out.
Mostly, the central leaves of the plant die initially due to which the stem and a portion of the runners become bare. Light brown to black elongated strip appear on the stems and petioles. Due to warm and rainy weather, every leaf in whole crop may be finished which would show the field a burned over appearance.