Growing Butternut Squash

Butternut belongs to the cucurbit family of vegetable crops. It falls under the botanical group of Cucurbita moschata. The crop is a very nutritious vegetable whose fruit can be used with rice dishes and for making starter dishes such as soups. Butternut is a potential cash crop as it has a long shelf life.

1. Soils

Butternut can be grown successfully on a wide range of soils. Fertile soils with adequate drainage are ideal as butternut is quite sensitive to oxygen deficiency in the soils. The ideal soils are sandy loams or silty loams which warm up rapidly.

2. Rainfall

Water requirement is very high but high humidity encourages leaf disease and may affect flower production. The frequency of irrigation is largely dependent on soil type and weather conditions. Generally, for sandy soils in dry weather, the field should be irrigated at least every other day if not more often. The best test for the need of irrigation is to dig down and squeeze a handful of soil. If soil comes apart and does not stay in a ball upon the release of pressure it means that irrigation is needed.

3. Temperature

Butternut is more tolerant to high temperatures, thereby making it adaptable to low lying areas. It, therefore, can be grown in areas which are hot enough such as places where water melons can grow well. The temperature ranges for optimum production are 18 to 21°C at night and below 29°C during the day. This restricts production to the summer months with winter production possible in the Low veld areas or rather in the hot areas. The crop is very susceptible to frost.

4. Fertiliser Application

It is recommended that 10 to 15ton/ha of compost or manure should be incorporated about a month before planting or alternatively 500kg/ha of Windmill’s compound C (5:15:12) and 100kg/ha of Ammonium Nitrate (34.5% N) top dressing should be applied after the first fruits have formed.

5. Planting

Butternut can be planted from March to August and late July to mid-November in higher altitudes. Winter production is possible in low lying areas and this can be during the period March to August. For early production in high altitudes, sowing should be done from early July to August. The seed required is 2.5 to 3.5kg/ha. It can either be planted on hills, ridges or in furrows.

6. Weed Control

This is done mechanically using hoes.

7. Disease Control

Disease and symptoms (Windmill recommended control)

a. Anthracnose

Black angular spots appear on leaves with black streaks on stems and leaf stalks. Sunken lesions on the fruit produce spore masses under moist conditions. Spray Mancozeb/Dithane, or Chlorothalonil/Bravo.

b. Powdery Mildew

White mealy blotches on leaf surfaces. Spray Wetable Sulphur Carbenndazim or Bonomyl 50 WP, Funginex or apply Pedza Nhamo Dust at weekly intervals during susceptible periods.

c. Downey Mildew

Circular to rectangular small brown spots surrounded by yellow halo appear on the leaves. The spots are biscuit brown on the underside of the leaves or covered with a fungus and appear scattered. Under serious infection, the leaf dies from the edges inward resembling frost damage. Control weekly using Copper Oxychloride 85 WP, Mancozeb/Dithane, and Chlorothalonil. If done during the earliest stages of the disease they will provide adequate control. Ridomil Gold can be applied 10 day intervals up to a maximum of 3 sprays.

d. Leaf Mosaic

Leaves show dark green to light green mosaic with a blistered surface. Under severe cases, the plants remain stunted and do not bear fruit, and leaves will be malformed and curled. Aphid control is of utmost importance in curbing disease spread. Infected plants should be removed and destroyed.

8. Pest Control

Pest damage caused (Windmill recommended method of control)

i) Pumpkin fly - dry indented patch on fruit and subsequent rotting. Chemical sprays at beginning of flowering e.g. use Malathion 25 WP, Lebaycid, and Dimethoate 40 EC.

ii) Aphids transmit mosaic virus diseases. Control can be done using Dimethoate 40 EC, Diazinon, Metasystox, or Malathion 25 WP.

9. Harvesting

Fruits are harvested on a size basis in the region of 15cm length for the fresh market. The seeds should be soft. Fruits must not be allowed to ripen on the mother plants as this stops development of new fruits. Storage under shady conditions e.g. under a tree is ideal. This should be accompanied by good ventilation. Fruits showing signs of rotting should be removed.

10. Marketing

After harvesting, farmers should sort and grade their fruits according to size. Packaging varies according to size and market requirements. Farmers have the option to sell their butternuts at market places such as Mbare Musika, Chikwanha Shopping centre, Bulawayo Central Market, retail and wholesale outlets, colleges and boarding schools, or even to the export market.

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by Wonder Chakanyuka