Group Title: Mimeo report - Florida Citrus Experiment Station ; CES-67-20
Title: Economical citrus production practices
Full Citation
Permanent Link:
 Material Information
Title: Economical citrus production practices
Series Title: Mimeo report
Physical Description: 10 leaves : ; 28 cm.
Language: English
Creator: Reitz, Herman J., 1916-
Citrus Experiment Station (Lake Alfred, Fla.)
Publisher: Citrus Experiment Station
Place of Publication: Lake Alfred FL
Publication Date: 1967
Subject: Citrus fruit industry -- Economic aspects -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: Herman J. Reitz.
General Note: Caption title.
General Note: "200-1/5/67."
Funding: Citrus Station mimeo report ;
 Record Information
Bibliographic ID: UF00072448
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 76243036

Full Text

Citrus Experiment Station
Mimeo Report CES-67-20
200-1/5/67 Lake Alfred, Fla.


Herman J. Reitz
and the Citrus Experiment Station Staff
Lake Alfred

Citrus growers today have two overriding interests. One is to find profitable

markets for the large crop of fruit currently on trees, and the second is to use the

most economical grove production practices available, consistent with good grove

health and adequate yield of high quality fruit. On a dollars and cents basis,

there has always been ample reason for utilizing the most economical practices. If

fruit prices are high, this is a way to make additional profits. When fruit prices

are low, use of these practices is a necessity.

One of the most savored cliches in the citrus industry holds that there are as

many production programs as there are grove owners, and it is frequently added that

all these programs make money for the grove owner. This may be nearly true in

times of high prices, but when prices are low the choice of money-making practices

is much more greatly limited.

Most growers are in the business on a permanent basis, and must take a long-

term view and weather the occasional poor year. Efforts toward good management now

need to be intensified on all fronts, including the keeping of accurate grove

records, the efficient scheduling of grove operations, the economical purchasing of

all supplies, the competent handling of more or less fixed costs such as financing

and taxes, the marketing of the crop, and the actual making of choices of grove

practices to employ. Only the latter of these items is in the scope of this


Whether prices are high or low, groves must be maintained in a highly produc-

tive condition. The only return a grower receives from a grove operation comes

from the sale of fruit, and the more good quality fruit he has to sell, the greater

are his chances of making money on his grove. Certainly no one can now afford to

spend money on unnecessary grove operations of any kind or for frills, fads, patent

medicine, or magical remedies.

High fruit quality is as important as high yield. Fruit with the highest yield

of solids per box will find ready acceptance in the chilled juice and frozen concen-

trate outlets. Fruit with highest exterior quality, in desirable sizes, will find

an outlet in the fresh fruit market. Large amounts of money can be lost by running

scarred, disfigured, and green fruit through packinghouses. For fresh fruit, a high

pack-out is mandatory for a profitable operation. This is a much more important fac-

tor in years of low prices than in years of high prices, when all fruit, including

packinghouse eliminations, will pay a good return at the cannery. Crops of fruit

with low soluble solids, green color, disfigured by melanose and rust mite, will be

discriminated against in all the channels of the trade, and when fruit is plentiful

may never find a market outlet. In past years, there has been economic abandonment

of oranges, grapefruit, and tangerines in Florida, and low quality fruit is most

likely to meet this fate.

A grower may find it economically impossible to maintain a Spartan but ade-

quate program on all the groves under his management. In such cases, he might do

well to concentrate his resources into a thoroughly effective program on his most

valuable varieties, his highest producing individual blocks, and those most eco-

nomical to operate, while abandoning blocks affected with disease such as spread-

ing decline, fringe areas chronically affected adversely by water damage or recur-

ring cold injury, or blocks with undesirable varieties. This would be preferable

to scattering his resources over his entire acreage in a skimpy, ineffectual pro-

gram that would result in low yields or poor quality fruit.

For many years, the Citrus Experiment Station has joined with other agencies

in issuing recommendations on cultural practices. Some of the more widely


distributed of these are Bulletin 536B, "Recommended Fertilizers and Nutritional

Sprays for Citrus," the "Better Fruit Program Spray and Dust Schedule," and the

"Citrus Insect Control" series of articles issued quarterly, published in

The Citrus Industry. Numerous articles have been written on a timely basis as re-

search results became available. These recommendations have always been issued on

the basis of most economical production costs, whether fruit prices were high or low.

In the remaining portion of this article, the essential elements of an economi-

cal production program will be emphasized.


Spraying.- Spraying is the most difficult and costly of all the production prac-

tices in the grove. There are many species of insects and mites, several fungus dis-

eases, and at times nutritional deficiencies that must be brought under control.

There are numerous chemicals available to be chosen to fit individual situations.

Also, the operation of the spraying machinery requires great attention to details.

However difficult or expensive the operation may be, it is still necessary if high

yields of high quality fruit are to be produced, and productivity of the grove is

to be maintained.

The elements of a successful spraying operation include: grove inspection,

timing of the application, choice of materials, and operation of the equipment to

obtain good coverage.

Thorough inspection of the grove before spraying is necessary to learn which

pests actually exist in the grove, so that when the decision is made to spray, all

compatible materials needed to control the existing or threatening pests can be

included. It is much more economical to spray for a combination of conditions at

one time than to make repeated applications.

Timing of the postbloom and summer sprays is generally fixed by the stage of

tree growth or by the calendar. It is a very reasonable assumption that spray

applications will be needed in most groves at these two times. Inspection should be

sufficiently thorough to ensure that all threatening conditions are covered when the

application is made. During the remainder of the year, timing of sprays is more de-

pendent upon inspections to determine when the pests, primarily mites, are present.

In rust mite control, it is very important to spray before an increasing population

gets established on the fruit.

Considerable money will be expended for spray materials. Consequently, before

making a decision, a clear idea should be obtained as to the relative costs of ma-

terials for accomplishing the control of the pests present in the grove. This does

not necessarily mean that the cheapest materials are the best. For example, sulfur

is a cheap material and gives quick control of rust mite, but reinfestations fre-

quently occur in a short time. Further, scales and spider mites may also become

more troublesome if sulfur is used excessively. Therefore, sulfur should be used

only as an emergency treatment between the postbloom, summer, or fall mite sprays,

as discussed in the Spray Schedule.

Operation of the spray machinery should not be casually turned over to poorly

trained, indifferent help. This is especially true for low gallonage (high concen-

trate) applications. Calibration of the equipment to deliver the proper gallonage

is of the utmost importance. The spray pattern should be continuous and cover the

entire height of the tree. Approximately two-thirds of the spray should be de-

posited in the upper half of the tree. Competent personnel should ensure that the

calibration and rate of travel of the machine are as described in the Better Fruit

Program Spray and Dust Schedule. A good rule of thumb for gallonage per tree is

to use the number of gallons per tree equivalent to the height of the tree plus 5.

Thus, a 15-foot tree would require 20 gallons of dilute spray. Economies can be

made by concentrate sprays, but correspondingly, higher quality and better trained

help must be used in this kind of operation.

A great deal of money can be lost needlessly in the spraying operation, either

by putting on unnecessary materials or amounts of sprays, or by making inadequate ap-

plications. If, in hopes of saving money, a sprayer is sent into a grove to make a

skimpy, inadequate application, the grower might do well to cancel the entire opera-

tion and save all the expense. The results in pest control may be about the same.

Fertilizing.- Costoof fertilizing have been held down fairly well in the past

several years. One of the most common mistakes growers have made in recent years has

been excessive use of fertilizer. Groves do not need more than the amount of fer-

tilizer recommended in Bulletin 536B, and money need not be spent on fertilizers in

the more or less blind faith that some intangible benefit will be attained. Avoid

purchase and use of materials that do not carry a complete guaranteed analysis on

the fertilizer tag.

Most mature trees need not be fertilized more than twice a year. On finer tex-

tured soils in coastal areas, very satisfactory results will be obtained from one

application per year. Possibly the Orlando tangelo or the lemon, which seem to be-

come nitrogen deficient more readily than other varieties, would benefit from three

applications, but these varieties are exceptional. An application should be made in

late fall or winter and followed by one between the postbloom and summer sprays.

Timing is not very important and fertilizers should be applied when labor is avail-

able between other operations such as spraying, in which timeliness is of critical


For young bearing and mature bearing trees, 100 to 200 pounds of nitrogen per

acre per year and an equivalent amount of potash are recommended. Magnesium should

be used at the same ratio as recommended in Bulletin 536B. If phosphate is used

during the first few years in the life of a young grove, it can then be safely

omitted from many groves for several years. A soil test such as described in

Bulletin 536B will give assurance as to the adequacy of the phosphate status of the

grove soil.

As a general rule, it is more economical to use high-analysis fertilizer or

straight materials than to use low analysis fertilizers. Some growers still do not

distinguish between the cost of fertilizer on a per-ton basis and the cost on a per-

acre basis. It is the per-acre cost that is important. Growers should select the

cheapest fertilizer based on the recommended amounts of plant nutrients per acre.

For greatest economy, the materials used should be those that can be purchased by

the individual in his specific case for the least money per acre. Each grower will

have to determine what this is. All nitrogen sources have nearly the same value

when low or moderate application rates are used.

In most cases, the minor elements can be omitted until actual deficiency symp-

toms appear. For greatest economy, do not use zinc in sprays until at least some

traces of zinc deficiency appear in the grove.

It is not necessary to use manganese unless persistent manganese deficiency

symptoms appear on the foliage. Spray applications of manganese are likely to be

necessary only on calcareous soils. In groves with acid soils receiving mixed fer-

tilizers, manganese should be applied as manganese sulfate in the mixed fertilizer.

This simplifies the spraying program, and by reducing spray residue on leaves, tends

to decrease the numbers of insect and mite pests.

Unless actual copper deficiency symptoms appear, copper should be regarded

primarily as a fungicide. Where copper deficiency symptoms appear, the copper ap-

plication should be planned to utilize the fungicidal properties along with the

nutritional effect. This means the use of copper only as a fungicide in the spray


Boron deficiency cannot be readily identified by symptoms until damage to

fruit has occurred. Hence a preventive boron application should be included on a

yearly basis, either in sprays or fertilizers. The small amount of borax needed

in sprays will not upset insect and mite control very appreciably.

Liming in all cases should be based on a soil test. Whenever an application is

made, use not less than 1 ton per acre. It is not economical to make light, fre-

quent applications. In groves with high copper soil conditions, the use of high cal-

cium limestone is recommended to bring the pH up to an adequate level.

Irrigation.- Use of irrigation has greatly increased in central Florida in the

past few years, because research has proven that proper irrigation will increase

yield of most varieties. Irrigation should be used between the months of January and

June to prevent tree damage or production loss from drought. Irrigation between the

months of July and December does very little to increase yield, and should be used

in this period only to offset the occurrence of severe drought conditions that may

weaken the tree and lead to loss of the crop. Marsh grapefruit responds most strik-

ingly to irrigation, followed by Hamlin oranges, Valencia oranges, and Dancy

tangerines. Pineapple oranges respond very little to irrigation and should not be

irrigated in preference to making needed application on the other varieties.

Most irrigation has been done in the past by perforated, portable pipe. The

rate of application by this system is high and the system is entirely satisfactory

on fairly level land, except for high labor costs.

More recently, permanent systems have been installed widely. These are

fairly expensive to install, but quite economical to operate, primarily because of

the low labor cost. These systems are designed to deliver water at a very low rate,

of approximately 0.15 inch per hour, thus requiring 10 to 20 hours for each


Long duration of sprinkling has some disadvantages. If the application is made

during the day, wind frequently prevents a uniform application over the entire grove

area. Evaporative losses during dry, windy days may carry away over half the water

pumped. Under these conditions, salts may accumulate on the leaves to toxic

proportions. This is not important unless the total salt content of the water ex-

ceeds about 1000 ppm. If the sprinkling is done at night, fungus diseases such as

scab, melanose, and greasy spot are encouraged. Some of the fungi bringing about

biological control of scales and mites are also to some extent encouraged, a bene-

ficial effect.

The best practice seems to be irrigation at night, when usually the trees will

be wet with dew for several hours even without irrigation. The irrigation should be

terminated sometime during the following morning, so that the trees will dry off

thoroughly before the following night. This will interrupt the development of the

fungus disease organisms.

Excessive irrigation must be avoided. Weekly applications of irrigation water,

no matter how economically they are applied, are detrimental. Frequent irrigations

unnecessarily encourage the development of fungus diseases and are highly detrimental

to fruit quality, both internal and external. When an application is made, it should

be done with 1.5 to 2.5 inches so that the water needs of the tree will be adequately

supplied for several weeks. Usually no more than five or six applications per year

are needed, even in dry years.

If a grove must be sprayed and also needs irrigation, irrigate thoroughly first,

then spray. This avoids washing off the deposits of pesticides which have been

placed on the trees at considerable cost.

Cultivation.- Cultivation is beneficial only through control of weeds, and

should be held to a minimum. Clean cultivation as required to control weeds in late

fall, winter, and during the spring drought period will conserve soil moisture,

eliminate fire hazard, make the grove slightly warmer on cold nights, and facilitate

harvesting operations. Cultivation, mowing, or chopping during the summer may be

necessary to permit effective spraying, or even effective inspection of the grove.

Minimum cultivation of perhaps two times during the dry season and one additional

time during the summer to facilitate spraying would be just as satisfactory as any

other cultivation procedure and would be most economical.

Young, non-bearing trees must be relieved of serious competition from weeds and

from the hazard of foot rot infection during the summer growing season, either by

cultivation or by herbicides. The use of herbicides is new and cannot be adequately

discussed in this article. Several useful herbicides are recommended in Extension

Circular 303. Federal approval for the use of several others is hoped for in the

near future. For economical grove operation, growers should keep themselves

thoroughly informed on the latest developments in this field. Growth of weeds or

other cover crops in the middles between young trees is beneficial in reducing wind

erosion and sandblasting, particularly during the spring.

Grove Heating.- Cheap fruit will not pay much of a grove heating bill. However,

in case of a generally severe freeze, fruit might no longer be cheap. Also, growers

would be well advised to protect themselves against loss of bearing surface, since as

noted above, the only possible way to obtain an income from a grove operation is by

selling fruit. Generalized recommendations would indicate that for fruit protection,

firing should be considered if the temperature is predicted to fall below 280 for

four hours or more, and firing for protection of the tree is indicated if a few

hours below 240 is predicted. See Extension Circular 287 for more details about

the time to light heaters.

Replanting of Vacant Spaces.- Nursery trees today are not in short supply.

Fixed costs per acre are much the same, whether a grove has no skips or many skips.

Replanting in vacant spaces has always been a good idea, since eventually the

yield per acre will be almost directly proportional to the number of healthy trees

present. While it is too late now to increase production in the next few years by

replanting skips, the present economic conditions emphasize how important this

consideration is over the long-run. Nothing but the highest quality, virus-free


trees should be used and all replants should be of the same variety as the

balance of the block.

Pruning.- Hedging and topping of bearing groves should be continued. Hedging

facilitates the movement of equipment in the grove and facilitates effective spray-

ing. Topping tall trees eliminates the difficult and expensive operation of spray-

ing into the tops and also makes for lower cost of harvesting. Both operations

usually result in improved fruit size and color in tangerines, and increased fruit

size in grapefruit, thus improving pack-out.

Ideally, the removal of all deadwood is desirable for disease control, but

this operation appears to be uneconomic due to high cost of wages. Watersprouts

need not be removed from the center of the tree. They may produce fruit if not

shaded out.

Hedging and topping should be done before crowding occurs. Then only light

cutting is required, little crop loss results, and brush removal is not a serious

problem. Hedging or topping of tall, crowded trees is very expensive, and appre-

ciable reduction of the next crop can usually be expected. Light frequent pruning

is better than severe pruning at intervals of several years.


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