CULTIVATIONDISEASESPESTS

WATERMELON

satg

CULTIVATIONDISEASESPESTS

WATERMELON

Climate RequiRements....................................................4 a. TemperaTure........................................................................4 b. exposure.............................................................................4land PRePaRation..............................................................5 a. soil requiremenTs.............................................................5 B. propagaTion........................................................................5Planting................................................................................6mulCh......................................................................................7FeRtilizeR aPPliCation.....................................................8iRRigation..............................................................................9 Weed ConTrol.......................................................................9CRoP haRvesting..............................................................10stoRage...............................................................................10

damPing-oFF disease.....................................................12PowdeRy mildew..............................................................12angulaR leaF sPot.........................................................13

aPhids...................................................................................15whiteFlies...........................................................................15ePilaChna beetles...........................................................16Flea beetles.......................................................................16

Contents

Cultivation

Diseases

Pests

3

1m

30

cm

FURROW

CULTIVATIONCULTIVATION

X

4

ClimateRequiRements

STEP 1

hEalThy

Poor

Temperature

Watermelons are sensitive to very cold and very hot temperatures. The most appropriate temperature to grow watermelon is between 18°C and 35°C.

Temperatures above 35°C or below 18°C will result in poor growth or slow maturation

Exposure

Exposure to full, direct sunlight is necessary for the crop. For optimal growth, a minimum of 8-10 hours of direct sunlight per day is needed.

Propagation

The best soil temperature for seed germination is 25-32°C.

Prepare the field by plowing and harrowing thoroughly.

Remove any other plant remains.

Shape the land into beds which allows furrow irrigation of seedling and drainage after heavy rain.

Furrows should be 2m apart and the beds should be 2m wide and 20 - 30cm high.

BEd

5

land pRepaRationSTEP 2

2m

2m

20

-30

furrow

Note: If the soil is not warm enough (at least 21°C), place a black plastic film covering most of the soil beds to heat the soil. This also helps prevent weeds and pests.

Soil requirements:

Watermelon grows well on sandy loam soils that are well drained, and slightly acidic with a ph of 6.0 - 6.5.

3-4

cm

60-90cm 60-90cm

6

plantingSTEP 3

Mix plenty of compost or manure (at least 1 shovel full) into each planting hole.

Plant two-three seeds per hole, 3-4 cm deep into the soil.

Water well!

Separate the seeds 60 - 90 cm apart when planting into the soil.

Within a couple of weeks the seed should show signs of germination.

When two sets of leaves are showing, remove the weaker ones and leave the strongest seedlings to grow.

mixEd comPoST

7

mulChingSTEP 4

STRaW

Hay

CHoPPEd lEavES

When planting watermelons, apply mulch as it helps retain the moisture of the soil. It is recommended to use organic mulch, such as:

Mulching also provides food for the millions of microorganisms in the soil thus making the soil more nutritious for the plant.

8

FeRtilizeRappliCation

STEP 5

In order for resourceful development, watermelons need nitro-gen, phosphorus and potassium-based fertilizers. The maximum amount of these fertilizers required is 60 pounds/ha.

Fertilizer should contain several essential nutrients:

a general application of Urea is recommended before the timeof planting.

Nitrogen-based fertilizers such as ammonium sulfate or ammonium nitrate are extremely beneficial in regions such as Somalia.

NoTE

do not over water as it will decrease fruit development which results in blossom-end rot, and fruit splitting.

Hand Hoeing and Mechanical cultivation are the best methods to control weeds.

Using cultivation machines to prune the vines and roots decreases the development of watermelon and reduces yield.

Chemicals such as Metam Sodium can also be applied to suppress weeds.

WEEd conTrol:

9

iRRigationSTEP 6

1. Immediately after planting to allow fast and even emergence.

2. at early bloom, to prevent poor, underdeveloped fruit.

3. during fruit development to ensure good melon size.

Remember to water plants at 3 critical points:

NoTE

It is important to consider that different watermelon types take differ-ent lengths of time to fully mature.

For smaller types, the length of time generally ranges from 60-90 days, and larger watermelons can take 90-120 or more days to fully mature.

If you are hand pollinating your watermelon flowers, you may want to note that the flowers will be ready for pollination within 2-3 weeks of planting seeds, and the ‘fruit growing’ stage lasts for 1-4 months.

a metallic ringing means the fruit is immature.

A dull or muffled sound means the fruit is mature/over mature.

SToragE:

Thumping the watermelon determines the level of maturity

It is advisable to cut open a few fruits from various areas in the field to check maturity before harvesting commences.

Watermelons can survive in storage with temperatures between 11-15°C for about 2-3 weeks.

optimum humidity levels are between 85%-90%. Higher hu-midity may lead to stem-end rot.

Keeping watermelons at room temperature for up to a week can improve both color and flavor.

10

CRop haRvestingSTEP 7

11

DISEASESDISEASES

SymptomS and damage:

SymptomS and damage:

diSeaSe management:

diSeaSe management:

diseased seedlings undergo rotting and death of infected roots.

a white, cotton growth appears on infected tissues.

Fungal disease affecting a wide range of plants.

-Whitish powdery growth on upper leaf surface.-Fungal growth on surface.-Severely attacked leaves turn brown, dry and brittle.

meChaniCal ContRol-Use resistant varieties, if available.-destroy weeds.

meChaniCal ContRol-Use certified disease-free seeds.-Avoid fields with damping-off history.-leave wide spacing between plants.-avoid over-watering

ChemiCal ContRol-Plant only fungicide-treated seed.-drench soil with copper hydroxide.

12

Damping-off Disease

powDery milDew

13

SymptomS and damage:

diSeaSe management:

-Watery spots on leaves with variable sizes.-Initially, spots are water soaked.-affected leaf dries and shrinks.-Fruit spots are small, nearly circular and superficial.

meChaniCal ContRol-Use certified disease-free seed.-Practice crop rotation.-avoid run-off water from nearby overhead irrigation.

ChemiCal ContRollimit the soil where it is acidic.

angular leaf spot

PESTSPESTS

14

15

aphiDs

whiteflies

aphids are small bugs that suck the sap from plants and can cause extensive damage to crops.

Whiteflies are small white bugs that damage plants by feed-ing on the sap and coating them with honeydew.

meChaniCal ContRol-Control weeds.-Conserve natural enemies such as lacewings, bigeyed bugs, and minute pirate bugs.

ChemiCal ContRol-Spray with neem products-Spray with a selective insecticides (e.g. buprofezin)

-They suck plant sap.-Excrete honeydew where moulds grow, which may affect plant

-Suck sap from plants.-leaves become curled and twisted.-aphids also transmit virus diseases.

ChemiCal ContRolTreat plants with selective insecticides (e.g. pymetrozine, pyrimicab) when you notice aphids.

SymptomS and damage:

peSt management:

SymptomS and damage:

peSt management:

16

epilachna Beetles

Epilachna beetles are small yellowish beetles with a number of black spots on their wing cases.

-adults and larvae feed on leaves leaving a fine net of veins-damaged leaves shrivel and dry up-young plants can be entirely destroyed

ChemiCal ContRol-Spray neem extracts. Weekly application reduces the damage of the beetle significantly.

Flea beetles are black, brown or metallic blue-green beetles that are 1.5 to 3mm long and are known to chew holes in leaves.

adults chew small round holes (shot holes) in leaves. These pests are most damaging to seedlings.

meChaniCal ContRol-Thick mulches-Floating row covers

ChemiCal ContRolSpray botanicals or other alterna-tive products

SymptomS and damage:

peSt management:

flea Beetles

SymptomS and damage:

peSt management:

Recommended products:NeemRotenonePythrinGarlic Insecticidal soap is also reported

17

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