Avocado: How to Insure Productiveness, P. H. Rolfs and C. Rolfs.


Material Information

Avocado: How to Insure Productiveness, P. H. Rolfs and C. Rolfs.
Series Title:
Correspondence and Subject Files 1921-1943
Physical Description:
Mixed Material
Physical Location:
Box: 1
Divider: Subject Files
Folder: Avocado: How to Insure Productiveness, P. H. Rolfs and C. Rolfs.


Subjects / Keywords:
Agricultural extension work -- Florida.
Agriculture -- Florida -- Experimentation.
Agriculture -- Study and teaching -- Brazil -- Minas Gerais.
Agriculture -- Study and teaching -- Florida.
Citrus fruit industry -- Brazil.
Leprosy -- Research -- Brazil.
Minas Gerais (Brazil) -- Rural conditions.
Escola Superior de Agricultura e Veterinaria do Estado de Minas Gerais.
Florida Cooperative Extension Service.
University of Florida. Agricultural Experiment Station.
University of Florida. Herbarium.

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4* 44

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P. 8. ~olfs, D. Sc.. (i)


C. Rolfs, B.S. (.)

A new epoch is beirg inaugurated in Brasil in the production

of this very nutritious and delicious salad fruit. Very few visitors

to the tropics hve h'.d the pleasure of eating an apetizing avocado,

with its delicate, nutty flavor nxd of exactly the proper consistency.

The ,-roduct one finds usually on the onar'.rts, or is served in the hotels

has about the same rel-.tion f to the "pedigreed" fruit tbht the coaon

run of mangoes h:, tob the beautiful and delicious Rosa. Or as the

usual "club picked" orange has t the luscious io tangerine. The

production of higJh gr:de :voc-dos t~ad its in.iT"I_? i rcy in 'erth America,

more than 3J years ago and has n:t yet reached the export stnge. The

nateLon:l demand is Licr:-ering more rapidly thsn the oroduction. In

North America the limiting f:.ctor is clin te, in ra.sil ths limiting

factor is orchard huso.:ndiry'"T Tha Felder:l district alone has enough

productive land, nccu, occ to produce no rc avocados than the whole

of south -rasil is p:ro.u';ng tolz..:-0
In this brief article the wri ters hop:u to discuss a highly

technical subject in non-te2inic.il lc-n.ueage. Over 90 -: of the avocado

trees in Brasil today ,.ro simply ,"boarders".. earlyy ll the others

produce fruit.of so .poor a qu.ity tha t like the low qualityy of man-

goes and or'niges, it is a drug on the market. Thts article blazes

th trait by which th.e -'lorid.anss vId ifrins trb.,wvled out of

the avocado Adlderness.

1J. Consultor' Technico de Agricultura Esto de inaLs-Gerais since 1929.
In 1921 was called from the "tate of fiorida, by Minas, to organize and
conduct her Agricultural College.
2). Helper of Dr. Roil's since 1921.

_ _I __

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THE THREE PRIMARY FACTORS. There are three primary fac-
tors any one of which will result in an unproductive tree or grove.

Very frequently the question is eskedt.IPhy is my avocado tree
unproductive ?" If one replies to this question ,-without further

information, his guess is likely to be w'onu two times our of three.
TEF FIRST Fi.CTOR is the environment, which include e the

presence or E.ben.cec of A)w Insects and, B), Diseases. Both must
be remedied by proper treatment of the pest or disease. C). Uncon-
genial sol o condition. The avocado tree prospers best whea the

soil is mellov:, deep, and .:ell drirned but at the same time one

that retains moisture well. oiif tA S oil becomes compacted by
tramping over or by ueing "cultiviatLd" with hoes, its surface be-

comes an impervious .la-yer The hr-le aneld surface also augments

greatly the loss of moisture .uriag the dry season and compels

the v;ater tb run off during the r.-Lny season, carrying with it

much valuable .Lant foxd. 'hess urcongenial soil conditions mani-

fact themselves by a prnrature dropping of the leaves. The remedy

is obvious, plow andcultivate. D).. Exhaustion of one or more

elements of .l'Lnt food. The remedyi is the &lulic-tion of a well

balanced foe-tilizer. This phase is ably discussed in Chacaram e
Quin;aes by the ieminent j'. kenezes, so v.ill not be entered into

Thruout most of the tate of Mines-Gerais, nitrogen as

vaell as microbe life is usually d eiciant in the soil. This can

be corrected by ;,rowing a cover cIop during the rainy season, while

should be incorporated with the soil at the beginning of the dry

season. Tnis treatment will gre-.tly augment the profits derived

from the application of the cimlrrcial fertilizer. Likewise the u

of stable manure or rotted coffee hulls will greatly aid the comme

cial fertilizer to produce beneficial effects.
THL S.;COND FACMEO making for sterility is a lack of proF

Cm1S pollenization. The avocados, like some wvrieties of apples,
pears, grapes, strawberries and many other plants, are self steriW

The process for occasioning cross pollenization in the avocado is

3 a

radicAlly, different from that in any other of our fruits. It is
briefly discussed by the writerss in Ch: cars a '.uintaes for
January, 19 2, (Vol. 45, No 1, p. 88.),

cuss more in detail. Careful calculations h!av shown that 90

of the bea-ring avocado trees produce only ten per cent of the crp.

This c:.lculation wEs r.iLde an seedling trees of crop bearing size and

age. No tter how excellent the environment (Fctor One), nor bow

perfect the :.frr';:n;ement for cross r.ollenization (Factor Two), an

over;-helmin, p sr cent of seedling avoc-do trees produce unprofitably'

small cops. This i;lrnt ible quality is c-lled "Inhezit.nrwe' Na-

ture has -rut a drviium on unproductivity. The tree under natural
con.itiions which pro.Lduces a heavy cro0 of fi'uit or seeds, so exhaust

its energy thereby that in later years it is unable to compete with
the surioundln t-rees for food and sunlight and is eliminated.
Or..nig:-s and z.angoes are only apparently exceptions to
this rule (irnhrited iunfr"luitfulness), they have been cultivated

({fdP ~/ /f// erown undor artificial conditions) for so many thou-
sEa:nrJ of ye.rs thpt the natural ancestors of many varieties are

A;.:?i.e from unfruitfulness there are many other qualities

that Etre transmitted by inheritance. Among thejmmay be mentioned

the gr.-itt difference in nutritive v.lueue de to a variation in fat
constant, which may be as low as five :er cent and anywhere up to

a.s high as thirty per cent. This quality is inherited independently

of fruitfulness. But a discussion of that question cannot be enterec

into here.

In the article referred to in Ch-ccaru.s a %uintaes, we

discussed very briefly the complicated mechanism by whichh the avo-
cado is' injured cross-pollenization. The germ in the seed carries

the inlerltrnce frao two parents, from the one that produced the
pollen as well as from the one that produced the pistil. As 9O %


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s.ivent of the spring gro th iis e:.fer:':.x ;.r srome pumoc:uturists.

It cnt.i ls. r work but ,;'oiuces a 1 r er tr.' in to. ye-.rs tiu"rn

o.s the budiin:; matiod.ci. .i- type pof gr:.ft ei :i1 yed is unitmoo-'t.nt.

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Inrchin is a nth.od that can be a- loyed -.Jiv: 'ta eously

when. on: r. ,:..ves valuable -voc-.do trees, :..L..'. est slishd in

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to ;the, scion. ,Let.t .th: mi tho of i 'ac ure r s Vt~e sc.me as is

el:-.loy.d :ith oth-,i' ecies.