Watermelon Plant Diseases and Their Control 
WILT—Entire plant wilts (at first only during 
hot part of day), and finally dies. Water vessels 
in wilted stems appear discolored. 
PREVENTIVE—Plant on new land whenever 
possible. At least, do not plant on same land 
oftener than once in 4 or 5 years. Gather and 
burn old vines after harvest. Plant resistant 
varieties such as Hawksbury No. 8, Blacklee No. 
45, Wilt Resistant No. 40, and Wilt Proof Kleckley 
No. 6, Variety No. 19, Missouri Queen No. 52. 
Treat seed as described in paragraph 6. 
ANTHRACNOSE—Black spots on leaves and 
stems. Young fruit becomes dark colored and 
shrivels when the stem is attacked. Spots on 
fruits are numerous, large and often of pinkish 
color. 
LEAF SPOT—Small, round, black spots on older 
leaves near base of stem. These leaves die and 
drop off. 
DOWNY MILDEW-Irregular black areas on 
leaves. Under moist weather conditions the entire 
foliage may be killed. Sometimes a faint, purplish, 
downy growth may be seen on the under side 
of the infected spots. 
TREAT ALL THE ABOVE DISEASES AS 
FOLLOWS: 
A combination of crop rotation, destruction of 
plant refuse, seed treatment and spraying or 
dusting are necessary to keep in check these 
diseases of watermelon. 
Seed should be treated by soaking in corrosive 
sublimate solution (1 tablet in 1 pint of water) for 
5S minutes. Rinse thoroughly in plain water and 
dry quickly. 
Spraying with 4-4-50 Bordeaux mixture or dust- 
ing with 20-80 copper-lime dust should be started 
at first appearance of foliage diseases. (It is 
safer to start spray or dust applications as soon 
as the vines reach 2 or 3 feet in length). Repeat 
treatment every 10 to 15 days. Remove infected 
or stunted melons from vines. 
BLOSSOM-END ROT—Discoloration and shriv- 
eling of the blossom end of melon. Decay pro- 
gresses inwards. 
ROOT KNOT—Elongated swellings or small, 
round galls on the roots of plants are common 
symptoms of the root-knot disease. The causal 
agent is a small worm, called a nematode, which 
is scarcely visible to the unaided eye. Plants 
affected with root-knot are lacking in vigor, 
stunted, and pale in color. Root-knot galls are 
ordinarily much smaller and more numerous than 
the large, more spherical swellings of crown gall. 
One might confuse root-knots with the nodules on 
leguminous plants which are produced by the 
beneficial nitrogen-fixing bacteria. These nodules 
are easily broken off from the side of the root, 
whereas nematode galls are swellings of the 
root itself and cannot be separated from the 
root. Another eel-worm, the meadow nematode, 
40 WILLHITE MELON SEED FARMS, Poolville, Texas 
injures some plants by causing tufts of rootlets 
without causing galls. The eradication, or even 
satisfactory control, of root-knot nematodes is not 
easily obtained. Fields infested with root-knot 
nematodes should be planted with grasses, 
cereals, or CROTALARIA spectabilis for several 
years. At the same time, all weeds should be 
controlled since many of them are hosts for the 
nematodes. Clean fallow of the soil with frequent 
cultivation during dry weather tends to reduce the 
nematode population through drying of the soil 
and starvation. 
STEM-END ROT—May appear in the field 
through wounds in the melon rind. Most fre- 
quent in shipments of watermelons. Infection 
takes place in the cut stem causing a dark, soft, 
watersoaked area near the stem. Decay pro- 
gresses finally shriveling the entire melon. 
TREATMENT—Spray or dust crop in field as 
outlined in paragraph 6. When packing for 
shipment cut off end of stem and paint fresh 
cut with paste made as follows: Dissolve 2 lb. 
copper sulphate in 3% quarts of boiling water 
(use enamelware vessel). Stir 2 lb. laundry starch 
into 1 pint of water and add to the above boiling 
copper sulphate solution, with rapid stirring. 
Boil until a thick paste is formed. Make up fresh 
paste for each treatment (a carload of melons 
requires 1 quart of paste). 
HAIL—Hail storms frequently cause heavy 
damage to various crops. All succulent plants 
and their fruits such as cotton, corn, watermelons, 
tomatoes, small grains, are affected. In addition 
to the above factors too much water in the soil, 
improper placement of fertilizer and high winds 
may cause severe and widespread damage to 
the crop. Little is known definitely concerning 
the control or treatment of injuries due to un- 
favorable climatic conditions. Maintenance of 
favorable soil moisture through plowing under of 
cover crops or the use of mulch may be helpful 
in certain cases. Affected plants should be 
pruned back after the injured parts have become 
distinct, to force normal growth. 
CUCUMBER BEETLES (Both Striped and Spotted) 
—These bugs are very deadly to most vine plants 
early in the spring and usually begin to suck them 
as soon as the plant comes out of the ground. Use 
a dust spraying machine (any kind). Mix one 
pound of arsenate of lead with twelve pounds of 
lime. Spray lightly underneath the leaves early 
in the morning while plants are moist with dew. 
Use just enough to slightly white the plant. Spray 
about every two days until plants are ten days 
old. After they are that old they cannot harm the 
plants. (See page 38 for Aphis control.) Get the 
bugs and lice early and you will have little trouble 
with them later. Black Leaf 40, 1 oz. bottle, 35c; 
9 oz. bottle, $1.05; 1 lb. bottle, $2.50; 2 lb. can, 
$4.50; 5 lb. can, $8.90; 10 lb. can, $13.75. All the 
above plus postage. You can get the lime at any 
lumber yard. 
Branch office—Weatherford, Texas 
