Palumbo,
J.C. and D.L Kerns. 1998.
Melon Insect Pest Management in Arizona. IPM Series 11. Publ. No. AZ1028.
University of Arizona, College of Agriculture and Life Sciences, Cooperative
Extension, Tucson, Arizona. 7 pp. URL: http://cals.arizona.edu/crops/vegetables/insects/general/melon.html;
http://cals.arizona.edu/pubs/insects/az1028.pdf
Melon production in the southwestern United States occurs primarily in
the desert growing areas of Arizona, and southern California. Cantaloupes,
Cucumis melo, and watermelons, Citrullus lanatas, are the
predominant melon types cultivated, but Persian, honeydew, crenshaw, and
casaba melons, Cucumis melo, are also grown on a limited scale.
These crops require irrigation throughout their production cycle and are
planted during two distinctive growing seasons. Fall melons are typically
planted from July-September, whereas spring melons are planted from January-March.
Melons reach harvest maturity in 85-110 days depending upon melon type,
variety, planting date and seasonal temperatures.
Although melons can be produced any time during the year, the growing
seasons are largely determined by the domestic melon market. Market prices
are usually highest during the late spring and fall when melon availability
from other growing locations is limited. Furthermore, prices can vary
considerably throughout the growing season, depending of melon quality,
demand and availability. Fruit quality, both edible and cosmetic, can
significantly influence the price a grower will receive for his crop.
Because of the high growing costs required to produce melons, growers
intensively manage their crops for the highest possible yield and free
of insect contamination.
Melons in the southwest are grown in very diverse cropping systems, where
a variety of vegetable, agronomic and seed crops are cultivated concurrently
throughout the year. Numerous insect species can be found on melon plants,
but only a few have been determined to be economically important. Most
of the key insect pests of melons are polyphagous and migrate into melons
from surrounding crops and weed hosts. Consequently, cultural management
practices can have a measurable impact on pest population dynamics, but
control with insecticides is often necessary to prevent reductions in
yield and quality. Discussed below are descriptions of several key insects
that cause economic damage to melons and the tactics commonly used to
manage infesting populations.
Ground Dwelling Pests
Field crickets, Gryllus spp.,
Description: Crickets are annual pests in fall melons, especially
where over-head sprinkler irrigation is being used. The adults are black
or brown and are 1.5-2.5 cm in length. Eggs are laid in damp soil both
within and outside of cultivated fields. Adults and nymphs are usually
present throughout the season, but appear to be most harmful at stand
establishment of direct seeded melon crops.
Damage: Crickets will reduce crop stands by eating the newly emerged
seedlings. When they occur in large numbers, they can quickly destroy
most of a field. Problems usually occur in fields planted closely to cotton
or sudangrass in August and September, where large numbers are capable
of migrating to seedling cantaloupes and watermelons.
Management and Control: Most damage occurs at night and
crickets hide during the day in soil cracks, ditches, weeds, and under
irrigation pipes. It is difficult to monitor for cricket abundance. Scout
the field by looking under the sprinkler pipe for cricket adults. In most
case, cricket activity can be determined by the visual estimate of damaged
seedlings. Immediate postharvest discing of fields aids in area wide control
of crickets. Direct seeded melons planted in close proximity to cotton
or sudangrass should be considered high risk fields and damage should
probably be treated as soon as the plants begin germinating. Insecticide-treated
baits are available that can be placed around field edges to control migrating
populations. Additionally, insecticides can be applied through the sprinkler
pipe during plant emergence.
Cutworms, Agrotis ipsilon, Peridroma
saucia, and Feltis subterranea
Description: All melons are susceptible to attack by several species
of cutworm larvae. Cutworm adults are medium-sized moths, usually brown
or gray with irregular spots and lighter hind wings. Females lay hundreds
of eggs singly or in clusters (depending on species) on leaves or stems
close to the soil. After hatching, young larvae feed on leaf surfaces
for a short period, but older larvae drop to the ground, tunnel into the
soil and emerge at night to feed. Mature larvae are robust, 2-2.5 cm long
with mottled brown or gray skin. Larvae tend to curl up into a C-shape
when they are disturbed.
Damage: Young plants are often damaged or killed by cutworms.
Cutworms typically cut off seedlings or young plants at or just below
ground level. Losses can be especially serious in fields that have an
abundance of organic matter, which attracts moths to deposit eggs. Larvae
usually hide in the soil under debris, or under clods during the day and
come out at night to feed. Some species can reduce the cosmetic appearance
of cantaloupes by scarring the undersides of mature melons.
Management and Control: Cultural controls can help minimize
cutworm damage. Areas with weeds, or crop residue or areas located near
alfalfa fields often have high populations. Pay close attention to fields
that follow small grains or alfalfa. Eliminate weeds from field margins
and plow fields at least 2 weeks before planting. Destroy plant residue
from previous crops and avoid planting fields coming directly out of pasture.
Several natural enemies attack cutworms but none are effective enough
to provide reliable control. After the crop emerges, monitor for cutworm
injury by walking the field when plants are in the seedling stage. Check
for wilted plants with complete or partially severed stems. Damage is
most often serious on the edges of fields, but stand loss can occur in
a clumped pattern throughout the field. If large areas are infested, treat
with insecticides when problems are first observed before stands are severely
reduced or fruit is damaged.
Seedcorn maggot, Delia platura
Description: The seedcorn maggot is a white, legless larva of
a small light gray fly that attacks the planted seed of cantaloupes and
watermelons during the spring. They can be particularly serious if there
is a cold period that prevents quick germination of the seed. Maggots
may overwinter as a larvae in the soil or hatch from eggs laid in the
spring. There usually have three-four generations per year, but only the
first is economically significant.
Damage: The maggot attacks germinating seeds or transplants, but
is only a pest in the early spring when the soil is cool. The maggots
bore into seeds or into the developing hypocotyl of developing plants.
Seedlings with seed maggots will wilt and die within a few days . Under
favorable growing conditions for melons (80-85°
F), little damage is likely to occur. The conditions that favor seed maggot
infestations include high levels of decaying organic matter and cool wet
weather. The flies can also be attracted to the commercially prepared
growing medium used to start melon transplants in the greenhouse.
Management and Control: Fields with heavy-textured soil
usually experience the worst problems with seedcorn maggots. Incorporation
of previous crop residues by discing or plowing well in advance to planting
helps to reduce the attractiveness of the field to ovipositing adults.
Avoid direct seeding or transplanting melons after root crops, cole crops
or fall tomatoes. Rapid seed germination greatly reduces the risk of infestation.
Late season planting may avoid the early season infestation of this pest.
A preventative seed treatment or transplant drench is the best method
of control when conditions are ideal for maggot infestation.
Darkling Beetles, Blaspstinus spp.
Description: Darkling beetles adults chew off seedlings, feed
on foliage, and occasionally on fruit that is on the soil. The adults
are from 3-6 mm long and are black or brown. Darkling beetles, which are
in the family Tenebrionidae, can be easily confused with predaceous ground
beetles (family Carabidae), which prey on various soil insects. The two
beetles can generally be distinguished by the carabids lack of clubbed
antennae. Darkling beetles are most active at night but can be spotted
moving on the ground during the day. They generally stay hidden in the
soil or within field debris. Larvae are cylindrical soil-inhabiting worms
that are yellow and range from 1-8 mm in length,. They are often referred
to as false wireworms, and are not consdiered economically important.
Damage: Darkling beetles are generally not a problem unless large
populations move into a field when plants are emerging. They usually invade
fields from weedy areas or crops such as cotton and alfalfa, so damage
is often first observed on field edges. Seedling plants may be girdled
or cut off at or below the soil surface. Once the plants have 5-6 leaves,
the beetles are usually not a problem. As the season progresses, feeding
can occur on flowers, on the undersides of leaves and on the netting of
mature melons. Under moist soil conditions, they can also bore into fruit
where it rests on the seed bed.
Management and Control: Several cultural practices can help reduce
potential problems associated with darkling beetles. Maintain fields and
ditches free of weeds. Water barriers placed around the field can aid
in reducing migrating populations. Reducing organic matter in the soil
by following or deep-plowing will minimize beetle reproduction. When beetles
are observed migrating into melons from surrounding fields, a bait placed
around the edges of the field will usually provide adequate control. Treat
fields with insecticides whenever beetles are readily observed feeding
on plants, flowers or fruit.
Foliar Feeding Pests
Leafminers, Liriomyza sativae and Liriomyza
trifolii
Description: Liriomyza leafminers can readily cause economic
damage to melons, particularly in fall plantings. The principal leafminer
species in the southwest include L. trifolii and L. sativae.
The leafminer adults are small, shiny black and yellow flies with a bright
yellow triangular spot on the upper thorax between the wings. Subtle differences
in color exist between adult L. sativae and L. trifolii.
Females puncture young leaves and oviposit eggs within the leaf. Numerous
punctures are made, but only a small percentage contain eggs. Both male
and female flies often feed at puncture sites. After a few days, larvae
hatch and begin feeding on plant mesophyll tissue just below the upper
surface of the leaf. Larvae emerge from the mines after completing three
instars, drop to the soil and pupate. Pupation and larval development
require about the same amount of time to complete, both of which are determined
by temperatures. The optimal temperature for development is about 85-90°F
and development ceases below 50°F. The entire
life cycle can be completed in less than 3 weeks under ideal conditions.
Several generations may be produced during each growing season in Arizona.
Damage: Mining of leaves by the larvae is the principal cause
of plant injury. Larvae mine between upper and lower leaf surfaces creating
winding tunnels that are initially small and narrow, but increase in size
as the larvae grow. These mines can cause direct injury to seedling plants
by removing chlorophyl and reducing the plants photosynthetic capacity.
Mines and feeding punctures also produce an entrance for pathogenic organisms.
Excessive leaf mining in older plants can cause leaves to dry, resulting
in sunburning of fruit and reduction in yield and quality. In severe infestations,
leafmining may cause plant death. Damage to mature plants can occur when
attempting to hold the crop longer for a second or third harvest.
Management and Control: Early season leafminer infestations are
common, but in most cases are controlled by numerous species of parasitic
wasps. The absence of these natural enemies can result in leafminer outbreaks.
Leafminers are seldom damaging to spring melons unless temperatures are
unusually high. Problems with leafminers in fall melons can occur in fields
planted near cotton or alfalfa if adults migrate onto emerging seedlings
in the absence of their natural enemies. Secondary leafminer outbreaks
can occur from the destruction of parasitoids by frequent insecticide
applications used to control other pests. Thus, evaluation of leafminer
parasitism is an important criterion to determine the need for control.
Young seedling plants should be monitored regularly for the presence of
adults, larvae and parasitized mines. Mining will initially be focused
on the cotyledons and first true leaves. Yellow sticky traps can assist
in determining when early migrations take place, and also help in determining
species composition. It is important to identify the predominant leafminer
species because L. trifolii is much harder to control with insecticides
than L. sativae. If populations of adults and larvae build to high
levels when seedlings have 4-5 leaves and parasitism is low, insecticide
treatments may be necessary to prevent economic damage. For older plants,
control decisions should be based on the number of unparasitized leafminers.
In watermelons, chemical treatment is recommended if an average of 15
to 20 unparasitized larvae per leaf are found. For cantaloupes, treatment
is recommended if an average of 5 to 10 unparasitized larvae per leaf
are found. Cultural management can help reduce potential problems with
leafminers. Avoid planting adjacent to cotton and alfalfa if possible.
Deep plowing after harvesting crops aids in reducing leafminer numbers.
Row covers applied at planting and removed at first bloom have been shown
to exclude leafminer adults. Melons plants that are not stressed for moisture
or by other environmental factors can better tolerate leafminer injury.
Beet Armyworm, Spodoptera exigua
Description: Beet armyworm can occasional cause economic damage to
spring and fall watermelons in the southwest. Eggs are light green in
color and are laid in irregular clumps or masses, usually covered with
hairlike scales.Young larvae will feed in groups and spin webs over the
underside of the foliage where they are feeding. Larvae vary in color,
but are usually dull green with light colored stripes down the back and
a broader stripe along each side. Beet armyworms usually have a dark spot
on the side of the body above the second true leg. Mature larvae vary
in size but are usually about 3-4 cm. in length. The moth has grayish
brown forewings with a pale spot in the midfront margin, and the hindwings
are white with a dark anterior margin. Larval development varies with
temperature but normally requires about 3 weeks during fall crops.
Damage: The beet armyworm is primarily a foliage feeder, but damages
watermelons in particular by attacking immature fruit. The injury caused
by fruit feeding is superficial and little loss would result if not for
the cosmetic blemishes left on mature melons and fruit rot that may occur
from decay organisms that enter the wounds. The larvae will occasionally
develop inside the fruit, causing abnormal development and abortion of
the fruit.
Control and Management: Check surrounding vegetation for the presence
of beet amyworm larvae. Sanitation along field borders is important as
beet armyworms often migrate from weedy field edges into newly planted
fields. Populations of this pest also tend to build up in cotton and alfalfa
during gt he summer. There are natural enemies and entomophagous viral
pathogens that will attack populations of armyworm larvae, but may not
always provide reliable control. Montor watermelon fields by checking
developing fruit for larvae and feeding damage. Treat with insecticides
only if amyworm feeding is observed on the fruit. To conserve natural
enemies important for the natural control of leafminers, consider using
Bacillus thruringiensis sprays if small larvae (1st and 2nd instar)
are present.
Cabbage Looper, Trichoplusia ni
Description: The cabbage looper can be a destructive pest of all melon
crops. Cabbage loopers occur on both spring and fall melons. Populations
can be especially prevalent in the fall, when newly-planted seedlings
are emerging. Cabbage looper moths lay single, dome-shaped eggs on the
under side of older leaves. The larvae are light green in color and have
a distinctive white stripe along each side of the body. The larvae have
two sets of legs in the front of the body and three sets of fatter, unjointed
prolegs at the rear causing them to move in a "looping" manner,
arching the middle portion of the body as they move forward. Cabbage looper
pupae appear as greenish to brown pupa wrapped in a delicate white cocoon
of fine threads usually attached to the underside of the leaf. The moth
is mottled brown in color, and has a small silvery spot (sometimes a figure
8) near the middle of its front wing.
Damage: Loopers injure plants by feeding primarily on the underside
of leaves, leaving ragged holes in them. In fall crops, high populations
can chew seedlings severely enough to kill them or slow growth enough
to inhibit uniform maturing of the crop. In cantaloupes, larvae may move
to the mature fruit and feed on the netted surface causing cosmetic blemishes.
Management and Control: The cabbage looper has many natural
enemies that will keep larval populations below damaging levels unless
disrupted by insecticide applications. Several parasitic wasps (both egg
and larval parasitoids) are important natural control agents. The tachinid
fly, Voria ruralis, also attacks developing loopers. Under ideal
environmental conditions, a nuclear polyhidrosis virus that occurs naturally
in fields may control looper populations. Cultural control tactics employed
for beet armyworm are also recommended for management of cabbage looper.
Monitor for larvae and eggs by looking on the underside of leaves. Insecticide
treatments are recommended if larvae feeding on the leaves can easily
be found. In addition, adult flights monitored with pheromone traps and
observations of egg deposition can be used to time treatments. Cabbage
loopers are particularly susceptible to Bacillus thuringiensis,
but should be applied when eggs start to hatch and larvae are small.
Sucking Pests
Two-spotted Spider Mite, Tetranychus spp.
Description: Spider mites are widespread on melon crops throughout
the southwestern U.S, but only occasionally cause significant damage.
Spider mites are very small and are diff difficult to see with the
naked eye. Adults are about 0.45 mm long, have eight legs and an oval
body. Tiny spherical eggs may be present as well as webbing. Spider
mites develop numerous generations throughout each melon growing season.
Under optimal conditions of high temperatures and low humidity, mites
can complete their life cycle in five to seven days.
Damage: Spider mites injure melons by puncturing the surface cells
on the underside of leaves where they feed. This results in the destruction
of chlorophyl and reduction in photosynthetic activity. Injured leaves
become pale, stippled and can dry up and die under heavy infestations.
Injury often is not noticed until reddish brown patches of affected plants
appear in the field. Injury is most common in hot, dry weather from late
spring to early fall when temperatures are favorable for rapid development.
Light infestations can be tolerated, but severe injury can result in lowered
yields and reduced fruit quality.
Management and Control: Spider mites feed on a large number of
crops and weeds, and will overwinter in soil and debris on the ground.
Infestations in melons often begin with adults carried by wind from adjacent
crops. Because dust favors spider mite populations, minimize dust by watering
field roadways. Several natural enemies (including predatory mites and
thrips, minute pirate bugs and lacewings) play an important role in regulating
mite populations below economic injury levels. Predator populations should
be encouraged by limiting chemical rates and numbers of applications for
other insect pest. Good irrigation and fertilization management increases
plant tolerance to mites. No economic thresholds have been established
for spider mites. However, treatment with an acaricide is recommended
when webbing occurs before vines reach 14 inches in length and predatory
mites and thrips are absent. Because spider mites inhabit the undersurface
of leaves, thorough spray coverage is important.
Sweetpotato Whitefly, Bemisia tabaci
Bstrain; also known as Silverleaf Whitefly, Bemisia argentifolii
Description: In the past few years, the sweetpotato whitefly has shifted
from a position as a secondary pest (virus vector) to being the primary
pest in fall vegetables, melons and cotton in the southwest. This shift
in pest status is thought to have occurred due to the development of a
new strain of the sweetpotato whitefly (Bstrain), or as it is sometimes
referred, the silverleaf whitefly. The adult is a small insect, about
1-1.5 mm long with the body and wings covered with a whitish powdery wax.
Eggs are minute (0.2 mm), oval, yellow and attached to leaf tissue. Near
hatching, the egg will darken in color. Adults and eggs are most prevalent
on the lower surface of younger leaves and the scalelike nymphs on older
leaves. Crawlers (first instar nymphs) are yellowish in color and are
oval and flattened in appearance. They are 0.2 to 0.3 mm in length, and
will move about until they locate an acceptable feeding site (a minor
vein). They then become immobile and remain so through four nymphal instars.
Late third and fourth instar nymphs have distinctive red eye spots and
are termed redeyed nymphs. At the end of the fourth instar they enter
what is called the pupal stage. Their pupal cases are dome shaped and
oval in their outline, and are 0.7 to 0.8 mm in length. Whiteflies complete
2-3 generations in spring melons and can complete their life cycle in
a short as 16 days during fall growing conditions.
Damage: Although the sweetpotato whitefly has a wide host
range, one of its preferred hosts is cantaloupes. It has become a serious
pest on melons because of its high reproductive capability, wide host
range, high rate of feeding, exudation of sticky honeydew and habit of
feeding on the undersides of leaves where they are protected from insecticide
sprays. Adults and nymphs feed on melon leaves by inserting their tubular
mouthparts into vascular tissue and extracting plant assimilates (carbohydrates
and amino acids). They also injure developing plants by destroying chlorophyll
and reducing the plants photosynthetic activity. Heavy populations on
young plants can cause desiccation of leaves and plant death. Whitefly
populations cause serious economic damage to melons crops by reducing
fruit quantity and size. Fruit quality is also impacted by the lowering
of soluble sugars in the fruit and by the contamination of fruit with
honeydew which gives rise to sooty mold.
Management and Control: Whitefly populations will build
in cotton and alfalfa, so growers should pay particularly close attention
to melons planted downwind or adjacent to these fields. For spring melons,
termination of winter vegetable crops immediately following harvest is
important in the area wide management of whiteflies. Although several
parasitic wasps (Encarsia and Eretmocerus spp.) are effective
parasitoids of sweetpotato whitefly, populations of these natural enemies
are not capable of naturally controlling whitefly populations under southwest
growing conditions. Thus, melons planted in high risk situations (late
spring and fall plantings) should be treated prophylactically with a soilapplied
systemic insecticide. Melons planted in January and February when temperatures
are cool and when there is no significant source of whiteflies in a one
mile radius, should be treated as needed with foliar adulticides. Whiteflies
are best controlled by preventing immature populations from colonizing
plants; do not allow adults to build and lay eggs. Melons should be monitored
as soon as the plants emerge. Sample for whiteflies early in the morning
when the adults are sedentary. A presence-absence sampling plan has been
developed for whiteflies on cantaloupes. To estimate whitefly abundance
requires that 50 leaves be randomly sampled in each field. When greater
than 60 percent of the leaves are infested with one or more adults then
an insecticide treatment should be applied to prevent economic damage.
Best control is usually achieved from tank mixing insecticides . Good
spray coverage is essential for adequate control. If possible use ground
application equipment that delivers spray at high pressure and volumes.
Green Peach Aphid, Myzus persicae
Description: The green peach aphid occurs throughout the Southwest
and has a wide host range. The green peach aphid is generally considered
to be a pest in spring melons. The winged adult stage is of primary concern
because of their ability vector viral diseases. Winged green peach aphid
adults have a black/brown head and thorax. Their abdomen is light green
or red with a black/brown mottling. At the base of each antenna of many
aphids is a small bump called a tubercle. In green peach aphids these
tubercles are pronounced and converging inwardly, while similar species
tubercles are less pronounced or diverging. Wingless adults are light
green or red with the same antennal bumps. Nymphs appear as smaller versions
of the wingless adults. The life cycle of the green peach aphid is typical
for aphids. In southern climates it reproduces asexually. In response
to crowding by other aphids or declining host plant quality, migratory
(winged) forms are produced that move to new hosts (weeds or crops). This
ordinarily occurs in the early spring.
Damage: The major injury from green peach aphid is a result of
virus transmission. Watermelon mosaic virus, zucchini yellow mosaic virus,
and papaya ringspot virus are transmitted to melons primarily by the green
peach aphid. The spread of virus to a melon field is due to the movement
of winged forms during the spring. Green peach aphids move into spring
melons fields in large numbers from surrounding crops and weed hosts,
carrying viruses. Within field spread occurs as aphid feed and move from
one plant to another. The incidence of these viruses causes significant
reduction in melon yields and heavy virus infection can result in total
yield loss. Incidence of green peach aphid and its associated viruses
are rare in fall planted melons. Severe colonization of green peach aphids
can reduce plant growth due to removal of plant fluids, but this aphid
is rarely numerous enough to cause economic injury.
Management and Control: Green peach aphids are often most
numerous in fields containing weedy mustards and members of the goosefoot
family. Control of these weeds may help prevent buildup of green peach
aphid. Naturally-occurring populations of predators, parasitoids and entomophagus
fungi may provide effective control in early spring. Green peach aphids
can be excluded from plants by placing row covers over the seed bed following
planting until first bloom. Reflective mulches have also been shown to
be effective in repelling aphids from plants. Because of the short feeding
time required for these aphids to transmit viruses, insecticide treatments
will not prevent virus introduction, but may reduce the spread of the
virus within the field. Monitor for aphid flight activity and species
composition using yellow sticky traps. Melons planted in January and February
prior to peak aphid flight should be prophylactically treated with a soilapplied
systemic insecticide at planting. The decision to treat for aphids should
be based on the presence of winged forms in the field.
Melon Aphid, Aphis gossypii
Description: The melon, aphid, also called the cotton aphid, is
a small dark species that ranges in color from yellow to black. The winged
adults are about 1.5 mm in length and not quite as robust as the wingless
mature form. The melon aphid develops in aggregated colonies and is distributed
primarily on the underside of leaves. This aphid species appears in high
numbers in the cooler spring months, but unlike the green peach aphid,
melon aphid populations can be found infesting melons when temperatures
are warm. They reproduce parthenogenically and develop at a very high
rate under ideal growing conditions. They can also be serious problems
on fall melons. Melon aphid has an extensive host range including, cotton,
citrus, and many summer annual weeds.
Damage: Similar to green peach aphids, the melon aphid is a known
vector of several viruses. However, they can also cause injury to melons
through their feeding. They can be a major problem on young plants where
they cluster on the terminal growing points of the developing vines, distorting
and curling the leaves, and producing large amounts of honeydew. Feeding
damage can lead to loss in plant vigor, reduced growth rate and plant
death. Melons aphids will injure all melon types grown in the southwest.
Management and Control: The same cultural control tactics used
for green peach aphid should be employed for management of melon aphid
populations. Numerous naturally-occurring predators and parasitoids will
attack melon aphids and are capable of them under control if not disrupted
by insecticide applications. Melon aphid is very difficult to control
with insecticides. No thresholds have been established for timing treatments,
but applications should be made if large numbers of aphids build up early
in the season and natural enemies are absent. Early treatment does not
prevent virus transmission, but may reduce within-field spread of the
virus.
Fruit Feeders
There are several insect species discussed in the above sections that
damage immature and mature melon fruit. Species that feed on the fruit
such as cutworms, darkling beetles, cabbage loopers and beet armyworms
are important because of the cosmetic blemishes and fruit rot their feeding
causes. Although sucking insects such as whiteflies and aphids don't actually
feed on the fruit, their feeding activity on leaves can contaminate and
reduce the quality of otherwise marketable melons by the exudation of
honeydew.
Pollination
Because cantaloupes and watermelons are monecious, pollination by bees
is essential for the production of high quality melons. Colonies of honeybees
have to placed in or around fields to ensure pollen transfer from staminate
to pistillate flowers. Insufficient pollination will result in misshapen
melons. To produce high quality melons, it is recommended that 2-3 hives
per acre be placed in each field. Consequently, extreme care must be taken
with pesticides to prevent the destruction of honey bees. Some insecticides
used in melon pest management programs are highly toxic to these pollinators.
Bee kills are likely to occur when crops are treated with insecticides
during the blooming period. Losses can result from direct sprays on bees,
drift onto hives or adjacent fields, and by contamination of drinking
water, pollen or nectar. The following practices are very important in
planning pesticide applications. If possible, avoid making pesticide applications
when melons are in bloom. If applications are necessary during bloom,
apply the pesticide that is least toxic to bees and will still control
the target pest. Spray during the evening or early morning when the bees
are not actively working in the field. Finally it is very important precaution
that the beekeeper be notified before aerial applications are made. The
advance notice allows beekeepers to take necessary steps to move or protect
their hives.
Selected References
Anonymous. 1993. Cucurbit Pest Management Guidelines. Univ. Of California,
Div. Agric. Nat. Res., Statewide IPM Project, Publication 3339, 56 p.
Cuperus, G. and J. Motes. 1987. Cucurbit production and pest management.
Oklahoma St. Univ., Coop. Extn. Circ. E-853, 40 p.
Foster, R., G. Brust, and B. Barrett. 1995. Watermelons, muskmelons and
cucumbers, pp. 157-168. In R. Foster and B. Flood [eds.], Vegetable
Insect Management, Meister Publishing Co., Willoughby, OH.
Kerns, D. L. and J. C. Palumbo. 1995. Using
Admire® on desert vegetable crops. Univ. of Ariz., Coop.
Extn. 195017, Tucson. IPM Series No. 5.
Kerns, D. L., J. C. Palumbo and D. N. Byrne. 1995. 1995 Insect pest management
guidelines for cole crops, cucurbits, lettuce, and leafy green vegetables.
Univ. of Ariz., Coop. Extn. Publ. 195007, 34 pp.
Palumbo, J.C., A.Tonhasca, and D.N. Byrne. 1994. Sampling
Plans and Action Thresholds for Whiteflies on Spring Melons, University
of Arizona, Cooperative Extension, IPM Series No. 1, pp. 4.
Palumbo, J.C., A. Tonhasca, & D.N. Byrne. 1995. Evaluation of sampling
methods for estimating adult sweetpotato whitefly populations in cantaloupes.
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Riley, D.G. and J.C. Palumbo. 1995. Action thresholds for silverleaf
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Full Disclaimers
Issued in furtherance of Cooperative Extension work, acts
of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture,
James A. Christenson, Director Cooperative Extension, College of Agriculture
and Life Sciences, The University of Arizona.
The University of Arizona is an equal opportunity, affirmative
action institution. The University does not discriminate on the basis of race,
color, religion, sex, national origin, age, disability, veteran status, or sexual
orientation in its programs and activities.
Any products, services, or organizations that are
mentioned, shown, or indirectly implied in this web document do not imply
endorsement by The University of Arizona.
Information provided by:
John C. Palumbo, jpalumbo@ag.arizona.edu Associate Research
Scientist (Entomology)
David L. Kerns, dkerns@ag.arizona.edu
Associate Specialist, IPM (Entomology)
University of Arizona, Tucson, Arizona.
Material written June1998. |