Harvest and Handling
Melon yields vary depending on plant spacing, production methods (use of plastics, row covers, irrigation system), and variety. Average yield ranges from 15 to 30 tons/acre. Harvest and handling procedures vary with the type of crop grown and possibly with the intended market. Growers need to carefully supervise and train picking crews to prevent losses from improper harvesting (under/over ripe) and poor crop handling techniques.
Watermelons mature five to six weeks after pollination (cultivar and temperature dependent). The indicators of watermelon maturity are rind sheen, strong color differentiation between the stripes, creamy yellow color of the ground spot, and drying of the tendril nearest the fruit. Thumping is less effective, but a dull or muffled sound can indicate over-maturity. Ideally, it is best to cut a few melons in various parts of the field and compare these to other maturity indicators. A refractometer can help determine fruit sugar content and the BRIX values measured should be above 10. Harvesting and marketing under or over-mature fruits can hurt consumer interest and demand. Fruit sugar content does not increase after harvest but red color does continue to develop after picking. Fields are often harvested over a period of 2 to 3 weeks and may be picked once or twice a week.
An indicator for watermelon harvest is the drying if the tendril nearest the fruit.
To harvest watermelons, cut fruit from the vine, leaving some stem on the fruit. Watermelons should not be stood on end as flesh separation (hollow heart) can occur. Also, do not expose the ground spot to the sun to reduce sunburn. Over-stacking fruit piles can lead to bruising and compression injury both in the field and in storage. It is common to create small stacks of fruit in the field at harvest then to come later and load these into bins, trailers, or trucks. Typically, fruit are bulk loaded into 1000-pound cardboard boxes as these are easier to handle during loading, transport, and unloading. Few watermelons are graded here in Utah though specific markets may request some fruit sizing for their customers.
Cantaloupe, Honeydew, and Others
Harvesting specialty melons like cantaloupe and honeydews is very labor intensive. Melons need to be picked every few days and fields may be harvested over a period of 2 to 3 weeks. Length of harvest depends on vine quality, number of fruits, variety, and market demands. Fruit maturity takes four to six weeks after pollination depending on type, temperature, and season.
Cantaloupe are ready for market when fruits are at “half-slip”, well-netted, and of appropriate color for the variety. Half-slip is when the abscission zone between the stem and the fruit is partially formed and it takes a slight pull to separate the fruit from the vine. Cantaloupe harvested at half-slip allows sufficient time from harvest to market so that fruits do not arrive over-ripe. Typically, fruit are loaded into 1000-pound cardboard boxes for transport to markets.
An indicator for cantaloupe harvest is when fruits are well-netted.
Honeydew melons are cut from the vine at maturity. Honeydews are ripe and ready for market when plants have achieved normal size, when the ground spot turns a creamy or a light yellow color, when a waxy “bloom” develops on the rind, when the blossom end softens slightly, and when small micro-cracks form near the blossom end (Fig. 6.1). Honeydews do not form an abscission zone where the stem and fruit meet so other maturity indicators are necessary.
Casaba, Crenshaw, and other specialty melons are cut from the vine at maturity. These melons are ripe when the skin color changes slightly from green to yellow and the blossom end of the fruit is slightly soft when pressure is applied with your thumb (similar to honeydew). Use a refractometer to test fruits for sugar content. Cantaloupe and specialty melons with BRIX values above 12 have sufficient sugar to meet market requirements. With all melons, cooling prior to shipping extends marketability, increases the time for the melons to reach maturity, and extends shelf life.