- Field Tomato Production Guidelines for Hawaii
Crop Production Guidelines |
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By: Hector Valenzuela, Randall T. Hamasaki, and Ted M. Hori
Assistant Extension Vegetable Specialist, Assistant County
Extension Agent, and County Extension Agent, respectively,
University of Hawaii.
INTRODUCTION
The tomato, Lycopersicon lycopersici, is the number one vegetable
crop in Hawaii in terms of popularity and market value. This
unique vegetable, a member of the Solanaceae Family along with
the peppers and the Irish potato, is a native of Central and
South America. Nutritionally a medium sized tomato (5.3 oz)
contains 35 calories, is rich in vitamin C, vitamin A, potassium,
and fiber. It is a warm season crop grown in Hawaii from sea
level up to 6000 feet in elevation.
In 1991 14 million pounds (6,400 MT) of tomatoes were consumed in
Hawaii of which 23% was produced locally in 230 Acres (95 Ha).
The farm value of local production of tomatoes in Hawaii for 1991
was about $3.1 million, with production concentrated in Kona, Mt.
View, Kula and Molokai. Local production has decreased
substantially over the past few years due to crop losses caused
primarily by the tomato spotted wilt virus (TSWV).
Flowering and Fruiting
The tomato is self-pollinated. Flowers are borne in clusters
which are located on the stem between the nodes. Tomatoes,
especially the large fruited varieties, are sensitive to high
night-time temperatures which may lead to lower fruit set or to
development of small, seedless fruit. Optimum temperature for
fruit set is 60-70F (15-20C). Fruits reach the mature green stage
about 27 days after fertilization. Environmental stress, such as
poor nutrition, unfavorable weather, or insect and disease
pressure may result in abscission during or after flowering.
Cultivars
Cultivar selection is one of the most important decisions made
during the crop production process. Selection of cultivars
adapted to the local growing conditions and seed quality are
significant production factors which deserve careful planning and
consideration. Cultivars developed by the University of Hawaii,
now over 15 years old, have resistance to bacterial wilt,
vascular browning, Fusarium wilt race 1, common races of
root-knot nematode (gene Mi), spotted wilt virus (gene Swa),
Stemphylium solani, and spider mites. Growth characteristics to
consider during cultivar selection include plant habit,
jointlessness, fruit size, shape, color, firmness, and
smoothness. Market traits to consider include pack-out, fruit
size and shape, ripening, firmness and flavor.
In Hawaii Celebrity is the industry standard for bush-type
tomato, but production of this semi-determinate cultivar has
decreased dramatically over the last few years due to its
susceptibility to Tomato Spotted Wilt Virus. Petoseed has
recently released hybrid cultivar PSR 55289 with resistance to
TSWV and with similar horticultural traits as Celebrity. However,
its availability in the future will depend on local grower
demand. See Table 1 for a list of cultivars adapted to Hawaii.
Table 1. Cultivars adapted to Hawaii
Cultivar Large Plum or Cherry
fruited paste type type
Open Pollinated
Healani +
Tropic* +
8222 +
8248 +
Roma +
San Marzano +
Large Red Cherry +
Royal Red Cherry +
Hybrid cultivars
PetoSeed PSR 55289 +
Celebrity +
N-52* +
N-65* +
N-69 +
BWN-21 +
Small Fry +
Cherry Challenger +
Cherry Grande +
Sweet Million +
* Require staking and pruning
Cultivars which have performed well in Hawaii based on Molokai
Winter trials (where spotted wilt has not been detected) include
Milagro, Celebrity, Carmen, Cavalier, and Carnival. In Molokai
Celebrity was the most productive with experimental yields of
over 50,000 lbs per acre (56 MT/Ha).
FERTILIZER RECOMMENDATIONS
Optimum pH
The optimum pH is 6.0-6.5. Liming to raise the pH to 6.0-6.5 may
aid in reducing fusarium wilt in the field.
Nutrient Rates
Fertilizer applications should be based on crop nutrient demands
and on stage of crop growth. Tissue and soil analysis will help
to determine how much fertilizer to apply, to complement the
nutrient levels already available in the soil. Soil samples
should be taken and appropriate fertilizers added as recommended
by University of Hawaii Soil scientists for that particular soil
type. Excessive fertilizer application, above crop needs, may
result in salt buildup, phytotoxic effects on plant growth,
ground water contamination, and capital losses due to purchase of
unneeded fertilizer. Recommended rates for Hawaii are 1,500 to
2,000 lb/Ac of 10-20-20 or similar type fertilizer, with half
applied at planting and the remainder 4-5 weeks later.
Supplemental 100 lb/Ac of urea or 200 lb/Ac of sulfate of ammonia
(lbs/acre) can be applied every 3 to 4 weeks after harvest
begins. Phosphorus is an important nutrient for root development,
flower development, fruit set, and to hasten fruit maturity.
On soils which test low for phosphorus apply 1,000 lb/Ac of
treble superphosphate. This is preplant applied in 12 inch (30
cm) bands in the plant row worked to a depth of 6-12 in (15-30
cm). Soil magnesium deficiencies are corrected with 150-200 lb/Ac
of magnesium sulfate. Minor crop magnesium deficiencies may be
corrected as needed with magnesium sulfate (epsom salt) sprays of
10 lbs/100 gallons of water per acre.
An adequate calcium supply is necessary to prevent blossom-end
rot in tomatoes. Calcium deficiencies are corrected with weekly
foliar calcium nitrate or calcium chloride applications at rates
of 10 lb/100 gal and 5 lb/100 gal respectively.
Fertilizer Placement
In non-mulched crops, apply all P and up to 1/2 of N and K prior
to planting, incorporating with disks or rototilling.
Supplemental fertilization during the growing season should be
banded on both sides of the row.
For drip irrigated crops apply all phosphorus, micronutrients and
20% to 40% of total N and K prior to laying the plastic mulch.
The remaining N and K is applied at levels corresponding with the
crop developmental stage. At the seedling stage apply weekly 2-5%
of the total N and K requirements. At the early fruiting stage
begin weekly applications of 10% of the total N and K
requirements.
Nutrient Tissue Analysis
Periodic nutrient analyses of foliage tissue may be used to
provide an estimate of a crop's nutritional status and serve as a
record of crop performance. The tissue analysis should be
calibrated with soil fertility levels, according to soil samples
taken before planting. For tissue analysis collect a young mature
whole leaf (petiole and leaflets), located below the last open
flower cluster. A representative tissue sample from a field will
consist of 25 to 100 collected leaves free from insect or disease
attack. The critical growth stage of phosphorus uptake is when
the first flower cluster develops, and tissue levels should thus
be maintained above 0.4% to avoid flower abortion. With rapidly
growing plants the calcium level must be maintained above 2.5%
from the first flower set and preferably throughout the plant
life cycle. Excessive nitrogen applications resulting in tissue
levels >5% will inhibit calcium and potassium uptake, reduce
internode length, and promote excessive vegetative growth.
Recommended optimum ranges for tomato are found in Table 2.
Table 2. Recommended nutrient ranges for tomato
Nutrient Range Target level
N 3.0-4.5% 3.0%
P 0.4-1% 0.5%
K 3.0-7.0% 3.5%
Ca 2.0-5.0% 3%
Mg 0.40-1 .5% 0.4%
Fe 100-250 ppm 120 ppm
Zn 25-150 ppm 25 ppm
Mn 40-300 ppm 75 ppm
Cu 5-25 ppm 10
B 25-100 ppm 25
Mo . .15-5.0 ppm .16
CULTURE AND MANAGEMENT PRACTICES
In typical commercial operations, tomatoes are grown in
polyethylene-mulched beds with drip irrigation. Irrigation and
fertilization can be monitored closely with drip irrigation. The
plastic mulch helps to maintain a high degree of water and
fertilizer use efficiency. Tomatoes are susceptible to damage
from wind and growers in windy areas should consider the use of
suitable windbreaks. Wind break your crop in wind-prone areas
with wiliwili (Erythrina), yuba cane, or other shrubs suitable to
your area. An in-field rotation may be conducted for the
following crop by rototilling the row where the windbreak was
grown and planting in the row and preparing the bed in that area.
Time to plant
In Hawaii tomatoes are grown year round at 1000-3000 ft (300 to
1,000 m)elevation; March through August at 3,000 to 4,500 ft
(1,000 to 1,500 m); September through May from sea level to 1,500
ft (500 m) elevation.
Field preparation
Plow the soil if a hard pan is present. Liming, when necessary is
broadcasted and disked along with any crop residue or weeds.
Bedding, fertilizing, and fumigating may also be conducted at
pre-plant.
Propagation
Tomatoes are normally transplanted in Hawaii to assure proper
stand establishment. Seedlings are transplanted 3 to 5 weeks
after sowing. About 1 oz of seed is needed per acre if seed is
transplanted and 2 lbs per acre if direct seeded.
Spacing
Bush tomatoes are spaced 3-4 feet apart in rows spaced 5-7 feet
apart. Trellised plants are spaced 14-24 inches apart on 5 feet
tall trellises with rows spaced 5-6 feet apart.
Transplanting
Seedlings are grown in containerized plastic or styrofoam
multi-cell packs or similar systems where the cell surface area
is 2 square inches (5 sq. cm). These seedlings can then be
transplanted with minimal disturbance to the root system. Early
root development is enhanced with soluble 10-52-17 or similar
fertilizer when applied at 3-4 lbs per 50 gallons of water. The
transplants are kept in a greenhouse or shade house. Follow
proper sanitary conditions by using sterile trays and soiless
growing media. The seedling should be carefully monitored to
maintain proper watering, nutrition, and disease-free material.
Training
Staked tomatoes provide ease of harvest and higher fruit quality
by keeping fruits off the ground and resulting in less rot.
Staked tomatoes are normally pruned to 1-2 main stems. Staking is
done 2-3 weeks after transplanting. Wooden stakes 50-60 inches
long are driven into the ground halfway between each plant or
between alternating plants. Plants are trained by tying the
plants with plastic twine or construction wire onto the trellis
beginning 3-4 weeks after transplanting and is repeated 3 or 4
times during the growing season. The twine is tied around each
stake and on both sides of the plant to provide vertical support.
Before re-using, stakes should be sterilized by steaming 1-2 hr
at 200F below a plastic tarp, or with methyl bromide fumigation.
Height of the stakes and training technique varies depending on
wind conditions during the growth cycle, or on traditional
practices followed in the different tomato production areas of
the state.
Irrigation
Drip irrigation for tomatoes has gained popularity because of
increased water use efficiency and because it allows for the
application of fertilizers and pesticides with the irrigation
water (Fig. 1). With drip irrigation it is possible to closely
synchronize weekly water and nutrient application rates with the
corresponding stage of crop development.
PESTS
Tomato yields may be reduced by a myriad of insect and diseases
pests. Integrated pest management (IPM) is a systems approach to
reduce pest damage to tolerable levels using a variety of
techniques such as natural enemies, genetically resistant plants,
sound cultural practices, and when appropriate, chemical
pesticides. The IPM approach is based on proper pest
identification, periodic scouting, and on the application of pest
management practices during the precise stage of the crop's
development where no control actions would result in significant
economic losses. Two additional strategies of an integrated
management approach consist of 1) Taking pest control actions
during the most vulnerable stage in the pest's life cycle (to
maximize results with the least possible effort), and 2) To
utilize synthetic pesticide spray applications for pest
suppression, only after all other pest control alternatives have
been considered and exhausted. The main objectives of utilizing
alternative pest controls over pesticide treatments, is to reduce
the high capital costs incurred with frequent pesticide
applications, and secondly to maximize the abundance of
beneficial organisms.
Insects
Important insect pests of tomato include aphids, armyworms,
cutworms, tomato fruitworm, leafminers, melon fly, mites,
root-knot nematodes, tomato pinworm, thrips, and whiteflies.
Outbreaks of the sweetpotato whitefly and the greenhouse whitefly
is currently a major problem for tomato production in Hawaii.
Apply insecticides only when necessary, and when possible rotate
pesticide families to delay development of insect resistance.
Insects with exploding population growth rates such as thrips,
whiteflies, mites, leafminers, and aphids are especially prone to
develop pesticide resistance, when exposed to frequent
applications of the same insecticide.
Aphids
Aphids feed on plant sap which may reduce plant vigor. Aphids may
also act as vectors of plant viruses, and may also introduce
toxins into the plant, resulting in growth deformations. Growers
should use timely insecticide applications as needed based on
close monitoring of aphids and their natural enemies.
Armyworms
Beet armyworm, Spodoptera exigua, and nutgrass armyworm, S.
exempta, infestations on tomato may result in up to 25% fruit
losses. The armyworms can be distinguished by the inverted
"Y" on the front of the head. Adult moths are active at
night and can lay eggs on the leaves in groups of 100 or more.
Feeding by young caterpillars can reduce leaves to veins leaving
behind webs. Caterpillars normally begin feeding on the fruit
after molting 3 or 4 times, and later pupate in the soil. Damage
to the fruit consists of superficial feeding wounds that dry out
as the fruit matures. Small caterpillars, however, may penetrate
the fruit and cause damage similar to the feeding damage caused
by the tomato fruitworm. A caterpillar normally feeds on more
than one fruit. Armyworms should be controlled before they reach
1/2 inch in length. Monitor the crop weekly beginning at fruit
set and apply pesticides when more than 0.25 larvae per plant are
detected .
Cutworms
These caterpillar pests which include the variegated cutworm,
Peridroma saucia, and the black cutworm, Agrotis ipsilon, can
devastate young tomato plants, by chewing through the stems at
the soil line. Cutworms are active at night. Control is warranted
when high populations are present in the field prior to planting.
Baits containing Bacillus thuringiensis are available for cutworm
control. Control is normally not recommended when the plants are
1 foot tall.
Tomato Fruitworm
The tomato fruitworm, Helioverpa zea, damages green fruit. H. zea
is also an important pest of corn, lettuce, beans, and other
crops. Eggs are laid singly on leaflets close to the small
fruits. The larvae feeds on green fruit and later burrows into
the soil to pupate. The pupa is formed in a tiny cell 2 inches
below the soil surface. Adults are active at dusk and during the
night. Female moths begin laying eggs 48 hours after emergence.
Important natural enemies of the fruitworm include the parasitic
wasps Trichograma spp., and Hyposoter exiguae as well as some
general predators. The critical period for monitoring begins at
flowering up until the green fruit stage. Egg counts are made
from leaves below the inflorescence. Pesticide applications may
be needed when more than four viable eggs are found in a sample
of 30 leaves. Pesticide treatments are also recommended when a
large percentage of young caterpillars are feeding on the foliage
before fruit damage has occured.
Leafminers
Leafminers are normally a secondary pest which are kept in check
by natural enemies. However both the vegetable leafminer,
Liriomyza sativae, and the celery leafminer, L. trifolii, may
become primary pests in tomato fields where intensive pesticide
use have destroyed their natural enemies. Leafminers are small
yellow maggots which form trails beneath the leaf epidermis as
they feed. When fully grown, the larvae drop to the soil to
pupate. A monitoring program consists of placing white styrofoam
or plastic pans at the soil level below the plant throughout the
field to collect larvae as they drop and pupate. Insecticides are
recommended when average counts rise above 20 pupae per pan per
day. Because contact insecticides won't reach the larvae inside
the leaf, systemics are recommended.
Melon Fly
The melon fly, Bactrocera cucurbitae, has long been a major pest
of tomatoes in Hawaii. The pest has traditionally been controlled
in problem areas with protein baits and an insecticide such as
malathion applied to corn border rows. Infested fruits should be
removed from the field to reduce insect numbers. Do not dispose
of culled fruit with live melon fly larvae in areas close to the
production field.
Mites
Outbreaks of carmine spider mites, Tetranychus cinnabarinus, and
the tomato russet mite, Aculops lycopersici, may occur during hot
and dry weather. Tomato russet mites are tiny spider-like animals
which feed preferentially on the lower stem, and then move on to
feed on the upper section of the plant and on leaves. Their life
cycle, egg hatching, and two nymphal stages until maturity, takes
one week in hot weather. Presence of the mites is manifested in
the bronze and greasy appearance of stem and leaves. Similarly,
the carmine spider mite completes its life cycle in about one
week. Its feeding causes leaves to become stripped with light
colored dots. Leaves may later turn yellow and drop. Silk webbing
may be present when infestation is heavy. Wettable sulfur, and
other miticides are effective on mites.
Root-Knot Nematodes
Root-knot nematodes are microscopic round-worms which feed on the
roots of plants. Symptoms on the foliage caused by the affected
root system include stunting, wilting, and leaf yellowing.
Infested roots develop gall-like swellings. Adult stages of the
nematode reside inside these swellings in the roots. Prior to
planting, tomato fields are normally fumigated for nematode
control. Many commercial cultivars, including the UH bred-lines
are resistant to root-knot nematodes. Several grasses, which are
non-hosts to the root-knot nematode such as oats, barley, wheat,
and rhodes grass, may also be grown before tomatoes. Other
nematodes which infest tomatoes include sting, stunt, reniform,
and dagger nematodes. The soil may be tested to estimate the
population of parasitic nematodes.
Tomato Pinworms
The tomato pinworm, Keiferia lycopersicella, are small
caterpillars which can severely damage tomato. Crop losses can
reach up to 80%, despite the application of insecticides. The
yellowish-green larvae is 1/4 inch long. Activity of the adult
moth peaks between 4:00 and 9:00 PM, in which eggs are layed
preferably in leaves just above or below the inflorescence. Young
larvae tend to leave in the leaves. The leaf tips are tied
together by the pinworm as it feeds, making it difficult to
target by insecticide applications. While some pinworms complete
their life cycle in the leaf, in most cases third instar larvae
perforate the fruit near the calyx area. The pinworm normally
pupates in the soil, but in some cases, it may pupate in the
fruit itself. Alternative controls for the pinworm include the
enhancement of parasitoids, clearing of weedy areas close to the
production field, quick disposal of the crop after harvest, and
establishment of crop-free periods. A monitoring program for the
tomato pinworm consists of weekly egg and larval counts,
assessment of fruit damage, and adult counts with pheromone
traps. Insecticide treatments are recommended when larval counts
are above 0.25 per plant.
Thrips
The western flower thrips, Frankliniella occidentalis, is a
vector for the tomato spotted wilt virus. This disease has caused
a dramatic decrease of tomato acreage in Maui over the past few
years. These thrips may also reduce plant vigor when feeding on
tomatoes in large numbers. Their direct damage to fruit may cause
a bronzing effect.
Whiteflies
Recent sweetpotato whitefly, Bemisia tabaci, outbreaks have
caused considerable losses in tomato fields state-wide. The main
symptom is an irregular ripening of the fruit, which is difficult
to distinguish on green-matured tomatoes. The irregular ripening
symptom which is probably caused by a toxin injected by the
whitefly, is visible only after ripening, when the tomatoes have
normally reached the wholesaler (Fig. 2). Additional sorting
operations, and an in-house ripening step may be required to
reduce the numbers of poorly ripened fruit. Full canopy coverage
with insecticide sprays is necessary to reach the eggs and adults
on the under side of the leaves. Area-wide control strategies may
be necessary in places where whitefly numbers are abnormally
high. The sweetpotato whitefly-transmitted gemini virus, which
has resulted in stunting and reduced fruit size in Florida and
California, has not yet been detected in Hawaii.
The greenhouse whitefly, Trialeurodes vaporariorum is also common
in Hawaii tomato production areas. Parasitic wasps and predators
such as the tomato bug help to keep the greenhouse whitefly below
damaging levels. In contrast to the case of the sweetpotato
whitefly, tomatoes can sustain greater population levels of the
greenhouse whitefly without yield reductions. Control strategies
will therefore vary depending on the specific whitefly species in
the field. Before conducting any pest control measures, identify
which whitefly species is actually present in your field.
Diseases
Bacterial canker
Cornybacterium michiganense can be a serious disease in tomato
because it can persist in the soil for many years, and because it
is seed-transmitted. Symptoms include wilting and cankers on stem
and fruits. Drip irrigation has reduced the incidence of this
disease. For control use disease free or certified seed.
Contaminated seed may be treated with the following treatments:
1) Fermentation: ferment crushed pulp for 96 hours before
extracting seed at temperatures near 70F. Stir it at least twice
a day.
2) Acid: Soak freshly extracted seed in an 0.8% acetic acid
solution. This is done by adding 1 fluid oz. of acetic acid to 1
gallon of water. Place seed in loosely woven cloth and immerse in
solution for 24 hr at 70F.
Bacterial spot
Xanthomonas campestris pv. vesicatoria may become a problem
during wet weather. Both foliage and fruits are affected.
Infection occurs through natural leaf openings or through wounds
in the fruit. Fruits show numerous 1/8 inch spots. Leaves show
irregularly shaped, brown spot lesions. Destroy tomato plants
after harvest to reduce inocolum levels.
Bacterial wilt
Pseudomonas solanacearum is the most serious disease of tomatoes
in the tropics and sub-tropics. Symptoms include rapid wilt and
death of the entire plant without any yellowing of the leaves. If
the stem is cut and placed in a glass of water, a gray bacterial
ooze is visible. The disease is difficult to control because it
remains in the soil for many years. Contaminated fields should be
rotated with non-solanaceous crops. Prevent machinery and field
personnel from moving from contaminated to non-contaminated
soils. The disease penetrates the plant through wound openings in
the roots. Old cultivars, Kewalo and BWN-21, developed by the
University of Hawaii College of Tropical Agriculture and Human
Resources are highly tolerant to bacterial wilt.
Blossom-end rot
This physiological disease may cause severe yield reductions in
tomato. The initial symptom will be a slight, water-soaked
discoloration on the blossom-end of fruits. The lesions enlarge
and turn dark brown or black. An irregular water supply
compounded with a fast growing crop may promote blossom end rot.
The disease results from a localized calcium deficiency in the
fruit. Calcium is translocated in the plant through the
transpiration flow. Being the major vascular system sink, the
leaves obtain the primary supply of calcium, and when calcium
deficiencies occur, the fruits will be the first organs to show
deficiency symptoms. Factors which have an effect on the plant's
calcium supply should be monitored including cultivar, plant
nitrogen status, soil fertility, pH, and an even moisture supply
in the root zone. Nitrogen over-fertilization may accentuate
blossom end rot by promoting excessive shoot growth.
Blotchy ripening or Gray Wall
This physiological disease also called internal browning is
characterized by irregular browning on the side walls of the
fruit. The fruits will develop a normal red color except in the
affected areas. A cross-section of affected fruits will show
brown veins with yellow to gray cells in the blotched areas. The
incidence of blotchy ripening is increased with tobacco mosaic
virus (TMV) infection, succulent growth, low potassium, and
sudden temperature changes. Commercial cultivars have good
resistance to this disease.
Catface
A physiological disorder in which fruits show extreme
malformation and scarring at the blossom ends. Catface results
from any growth factor that affects normal pistil development in
the flower. Prolonged heat during blossoming and other stress
factors may result in catfacing. Most commercial varieties are
not affected by catface. When possible remove affected fruits as
early as possible so that remaining fruits are allowed to
develop.
Double Streak Virus
This disease is normally a combination of TMV and potato virus X
or Y. A combination of tomato spotted wilt virus and potato virus
Y can also cause this disease. Initial symptom is light green
mottling of leaves followed by development of small grayish-brown
spots on leaves. Later, brown spots occur on stem and leaf
petioles. Infected plants are stunted and fruits, if produced,
are covered with dark spots. The virus complex is transmitted
mechanically. Controls include growing TMV resistant cultivars,
and the use of determinate cultivars which do not require pruning
(Fig. 3).
Early blight
Symptoms of the fungus Alternaria solani are concentric lesions
of dead tissue on leaves and stems, as well as spotting on leaves
and fruits. The disease can result in crop defoliation during wet
and warm weather any time during the crop cycle. Controls include
a three-year rotation, planting on wide, high beds, and fungicide
treatments.
Fruit cracks
Three common types of physiological cracks make fruits unsalable,
and permit the entrance of secondary disease organisms.
1. Radial: Cracks radiating from the stem
2. Concentric: Cracks extend more or less in a circular fashion
around the stem-end portion of the fruit.
3. Splitting of bursting: Occurs in nearly ripe fruit following
rain or irrigation.
Cracking can be partially controlled by providing an even
moisture supply, thus preventing alternating stages of fast and
slow fruit growth.
Fusarium wilt
Fusarium oxysporum f. lycopersici is a soil-borne fungi which
enters the plant through the root and interferes with the plant's
vascular system by stopping the transpirational flow. As a
consequence the lower leaves are first to turn yellow and wither.
The symptoms progress and eventually the entire plant is
affected, with a dark-brown discoloration in the bark of affected
areas, and with live leaves limited to the branch tips.
Commercial cultivars are available with resistance to races 1 and
2. In addition, sanitation, rotation with grass crops, soil
fumigation, and soil pH near 6.5 should be used for control of
races 1,2, and 3.
Gray Leaf Spot
Stemphylium solani begins as small circular sunken brownish
lesions with spots surrounded by a yellow halo. The fungus is
favored by hot weather, and can cause severe defoliation in
susceptible cultivars. Best control is achieved with resistant
cultivars. Promptly destroy the tomato crop after harvest.
Late blight
Phytophthora infestans causes severe defoliation, stem girdling,
and severe fruit rot. Cool nights and warm days with abundant
moisture favor development of this fungus. Fruit symptoms include
irregular watersoaked spots which turn brown and wrinkle at the
surface. Control includes careful monitoring and use of fungicide
applications.
Puffiness
This physiological fruit disorder is common during the winter or
early spring. Affected fruits are light and feel soft. Fruit
shape is normal but the surface is flattened or shrunken over the
sections between the internal walls. Fruit cross-sections show a
normally developed outer wall and poorly developed seed locules,
with existing cavities between the locules and the outer wall.
Factors which may promote puffiness include poor pollination,
excessive N applications under cloudy weather, excessive
irrigation, and temperature extremes.
Sclerotinia
Sclerotinia sclerotiorum can cause serious losses in both tomato
greenhouse and field operations. The fungus attacks the main stem
at the soil line and is characterized by watersoaked areas which
become light to dark brown. Further disease development results
in wilting and plant death. Masses of white mold and black
sclerotia are identifying characteristics. High moisture and
temperatures promote disease development. Control with proper
sanitation, soil drainage, crop rotation with grass crops, and
fungicide applications. This disease may build up in nearby bean
fields.
Tomato spotted wilt virus
Tomato plant growth ceases and senescence is promoted after
infection with spotted wilt virus (TSWV), perhaps the major
disease of tomatoes in Hawaii. In older plants, leaves near the
growing tips show dark, bronze or purplish, circular necrotic
spots. Fruits also show circular concentric marks (Fig. 4).
Tomato spotted wilt virus is the only virus known to be
transmitted by thrips. The only effective means of control are
resistant cultivars. Celebrity, the standard tomato cultivar in
Hawaii is highly susceptible to the new strain of spotted wilt.
Currently the PetoSeed hybrid PSR 55289 has shown resistance to
TSWV, and has comparable horticultural traits to Celebrity.
Tobacco mosaic virus
Symptoms include mottling or mosaic effects on the leaves.
Infections occurring when plants are young can significantly
reduce yields. The virus is transmitted mechanically, through
pruning, staking, and by field workers. Several commercial
varieties are resistant to tobacco mosaic virus.
Weeds
An integrated approach can be used to manage weed competition in
tomato production. The IPM program for weed control utilizes weed
identification, monitoring, sanitation, alternative cultural
practices, and timely herbicide applications. The use of a weed
map for each field will be helpful in the design of weed control
measures, and also as a record of weed problems in the field.
Cultural control practices for weed control include shallow
cultivation, plowing, disking, hoeing, crop rotation, cover
cropping, living-mulches, organic or plastic mulching and
herbicides. The benefits of proper field preparation can not be
overemphasized to improve tomato growth and also to minimize weed
problems during the crop growth cycle. Useful crops for rotation
with tomato include alfalfa, sugarbeets, and onions. Solanaceous
crops such as potatoes and pepper are not recommended as rotation
crops with tomato. Problem weeds in tomatoes include perennials,
dodder, weeds of the nightshade family (solanaceous family), and
grasses. The critical weed free period for tomatoes (that is the
number of days the field has to be kept weed free after
transplanting to prevent yield losses due to weed competition)
has been estimated to be between 30-35 days after transplanting.
HARVEST AND POST-HARVEST PRACTICES
Timing
Time from transplant to first harvest is generally 70 to 75 days
for cherry types, 75-80 days for the plum types, and 80-90 days
for the large fruited type tomatoes.
Production yields
Bush tomato culture in Hawaii: 20,000 lbs/Acre
Trellised tomato culture in Hawaii: 30,000 lbs/Acre
Average Florida yields: 30,000 lbs/Acre
Average Ohio yields: 13,500 lbs/Acre
Maturity
Tomato fruits mature about 25-30 days after pollination. Maturity
is correlated with increased fruit size, weight, specific
gravity, total acidity, and hydrogen concentration. Grades for
fresh tomatoes are U.S. No. 1, U.S. Combination, U.S. No. 2, and
U.S. No. 3. Fruit categories sizes for tomatoes are large 7.2 oz
(205 g), medium 5.3 oz (150 g), and small 4 oz (115 g).
Harvesting stages for tomato include immature green, mature
green, turning, half-ripe or pink, and ripe or red-ripe. Indices
of maturity for green picked tomatoes include 1) size, which
varies with cultivar; 2) rounded shape, not angular; 3) a whitish
green color development in the blossom end; 4) development of a
browny corky tissue on the stem scar of some cultivars, and the
preferred method of choice: 5) a representative sample of the
fruit's internal appearance (a destructive test). Both cherry and
plum tomatoes are normally picked vine ripe.
Harvesting operation
In large field operations fresh market tomatoes are hand picked
in 40-50 lb buckets and placed in bins, where a truck takes them
to the packing shed. An alternative harvesting operation consists
of a conveyor belt on ground tomatoes. Pickers travel a few feet
to the conveyor where the tomatoes are placed and conveyed into
the loading truck. Bruising of tomatoes from excessive handling
and unloading is significantly reduced with the conveyor belt
harvesting technology. Tomatoes should be maintained under the
shade until taken to the packing house where they are washed,
presized, sorted, graded, sized, packed, unitized for shipment,
and shipped to its destination market.
Washing tomatoes
Water for washing tomatoes should be at or above the temperature
of the tomatoes. Water with cooler temperatures will be absorbed
by the fruits. Wash water management practices should be an
important consideration during the handling process, to prevent
the spread of post-harvest diseases. Decayed fruit should be
culled to eliminate potential sources of inoculum. Wash water is
chlorinated at 150 ppm and fruits are held in this water for no
longer than 2 minutes as a single layer of floating tomatoes.
Presizing, Sorting and Sizing
Tomatoes with a diameter of less than 2 inches are culled. This
operation is carried through an automatic pre-sizer in large
commercial operations. Sorting and grading is conducted visually
in the packing house by separating tomatoes based on USDA color
stages. This operation takes on a double effort when sorting out
tomatoes with irregular ripening symptoms brought about by
sweetpotato whitefly feeding on the crop during the growing
season. Larger commercial operations in the mainland are moving
toward the use of automatic electronic color sorters such as the
ones developed for apples. Tomatoes are then sized based on
market classifications and conveyed to the packing line. Tomatoes
are normally packed in 25 lb cartons and unitized in 2000 lb
pallets.
Ethylene treatment
In Hawaii, some green picked tomatoes are treated with ethylene
to enhance and promote ripening uniformity. Some growers have
moved to ethylene treatment to overcome the irregular ripening
caused by the sweetpotato whitefly. However, preliminary research
conducted at the University of Hawaii College of Tropical
Agriculture and Human Resources did not show improved ripening
uniformity with ethylene treatment, instead it indicated the need
to improve harvesting techniques and training of the harvesting
crew to pick fruit at the same stage of physiological maturity.
Optimum ripening is obtained when the ripening rooms are
maintained at 68F and 90-95 relative humidity at ethylene
concentrations of 150 ppm. Ethylene is normally applied with
on-site catalytic generators or with flow-through systems.
Storage
Tomatoes should be stored at temperatures above 55F (13C). To
delay ripening of tomato at a particular stage they can be held
in a room below 68F (20C). Chilling injury occurs below 50F
(10C).
Packaging
Mature greens are sold in 25 lb bulk-packed cartons. Fruits are
packed in each carton based on fruit number per row and column in
a two layered tomato package. Pink and vine-ripe tomatoes are
packed in two-layer lug or tray packs. Cherry tomatoes are packed
in flats holding 12 1-pint boxes. Plum tomatoes are preferably
packed in quart boxes, 8 per carton. To avoid bruising don's
stack more than two layers high. Also pack the fruit stem up, to
protect the shoulders.
Table 3. Sizing of tomatoes1
Name Size Inches
min max
Maximum large >4x5 3 15/32 >
Extra large 5x5, 5x6 2 28/32 3 15/32
Large 6x6 2 17/32 2 28/32
Medium 6x7 2 9/32 2 17/32
Small 7x7 2 7/32 2 9/32
Extra small 7x8 1 28/32 2 4/32
1In Hawaii growers should check with the Hawaii Department of
Agriculture for current tomato grade standards.
Market Information
In 1990 the state imported about 14 million pounds of tomatoes,
or ~70% of the volume consumed locally. The potential for the
industry is to produce 100% of the local demand during the summer
months, and 40% of the market during the winter months. If the
industry could produce 70% of local demand the farm gate value
would be $8.46 million based on production of 13 million lbs and
the 1990 average per pound price of 65 cents.
A solid tomato production program includes a sound and well
planned marketing strategy. The prospective grower needs to have
a good understanding of annual market trends (see Figure 5:
Average monthly price and volume for tomatoes in Hawaii,
1986-1990, Figure 6: Hawaii tomato imports and local production,
1978-1990, and Figure 7: Monthly volume of tomato shipments in
the United States and imports, 1990), market competitors,
consumer needs, potential buyers, and market windows. To keep
abreast of changing market situations and new business
opportunities producers need to be in close contact with fellow
industry representatives, and with other business, university,
cooperative extension, and governmental organizations. Essential
to a producer's sound marketing program is also the need to have
a clear understanding of the farm's financial situation at all
times during the annual production cycle. Updated farm financial
records, and the input of financial information in budget
generators will help the grower to cut overhead and improve
efficiency of production. Updated financial information and well
organized farm records are also helpful in the loan application
process, in assessment of crop losses by unexpected pest
outbreaks, and will help the grower to make timely production and
financial decisions to take advantage of potential investment
opportunities, or unexpected market windows.
REFERENCES
Alvarado B. and J.T. Trumble. 1989. El manejo integrado de las
plagas en el cultivo de tomato en Sinaloa. CAADES. Sinaloa,
Mexico.
Dangler, J.M. and S.J. Locascio. 1990. Yield of trickle-irrigated
tomatoes as affected by time of N and K application. J. Amer.
Soc. Hort. Sci. 115:585-589.
Darby, J.F. Recent developments in the control of the major
diseases of unstaked tomatoes grown on the sandy soils of south
Florida. Proc. FL. State Hort Soc. 66:103-107.
DeFrank, J. 1986. Chemical weed control guide for tomatoes in
Hawaii. CTAHR Brief No. 054. Univ. Hawaii Coop. Ext. Serv.
Dhillon, P.S. and R.G. Brumfield. 1990. Greenhouse tomato
production in New Jersey. New Jersey Ag. Expt. Sta. P-02131-1-90.
Fox, J.A. and F. Killbrew. 1992. Cercospora leaf spot of
greenhouse tomatoes. Vegetable Press. Miss. Coop. Ext. Serv.
92:1.
Garton, R.W. and I.E. Widders. 1990. Nitrogen and phosphorus
preconditioning of small-plug seedlings influence processing
tomato productivity. HortScience. 25:655-657.
Harris, P. 1992. Controlling whiteflies on greenhouse tomatoes.
Veg. Press. Miss. Coop. Ext. Serv. 91,12.
Hassell, R. 1991. Plug quality starts with seed. Amer. Veg.
Grower. April. pg. 10.
Hochmuth, G.J. (ed). 1988. Tomato production guide for Florida.
Fl. Coop. Ext. Ser. Circ. 98-C.
Kretchman, D. 1990. Tomato disorders are preventable. Amer. Veg.
Grower. August. 38(8):14-17.
Nihoul, P., G. Van Impe, and T. Hance. 1991. Characterizing
indices of damage to tomato by the two-spotted spider mite to
achieve biological control. J. Hort. Sci. 66:643-648.
Sewake, K.T., A.H. Hara, W.T. Nishijima, and B.C. Bushe. 1990.
Questions and answers about integrated pest management. Univ.
Hawaii. Coop. Ext. Serv. HITAHR Brief No. 88.
Sheldrake, R. 1989. Tomato profits are in the bag. Amer. Veg.
Grower. 37(8), 24,26,28. August 89.
Sorensen, H.B. 1955. Methods of determining the optimum stage of
maturity for picking green-wrap tomatoes. Tx. Coop. Ext. Serv.
Bull. 820.
Wien, H.C. 1989. How Temperature Stress affects fruit set. Amer.
Veg. Grower. Aug. 56-57.
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