Google Answers Logo
View Question
 
Q: Irradiation Dose Necessary to Eliminate Anthracnose in Mexican Mango ( Answered,   2 Comments )
Question  
Subject: Irradiation Dose Necessary to Eliminate Anthracnose in Mexican Mango
Category: Science > Biology
Asked by: phytosan-ga
List Price: $50.00
Posted: 26 Nov 2003 09:56 PST
Expires: 26 Dec 2003 09:56 PST
Question ID: 280863
We are interested in obtaining research information as to the
irradiation tolerance /dose required to eliminate Anthracnose in
Mangos as a post harvest measure.

Request for Question Clarification by knowledge_seeker-ga on 27 Nov 2003 05:04 PST
Hi phytosan,

I?ve done some *very* cursory research into your question and here?s
what I understand so far (please correct me if I am misunderstanding
this):

1 ? Low-dose post-harvest irradiation extends shelf life of Mangos by
delaying ripening.
2 ? Delayed ripening means less chance of anthracnose infection
3 ? High-dose post-harvest irradiation kills insects that infest mangos
4 ? Too high a dose of irradiation causes damage to fruit
5-  Irradiation is not generally used alone to prevent anthracnose
infections, but is most effective when used in combination with other
treatments.

I didn?t find any studies that refer specifically to Mangos originating in Mexico. 

I have found very little in the way of first-hand scientific studies,
but have found several industry reports that include irradiation
dosages.


So..my questions to you are:

1 - Are we both talking about the Mango - Mangifera indica L. ?

2 - Do you need information specific to Mexico?

3 - What will you consider to be ?research information??  Will
industry reports with generally accepted dosages suffice, or do you
require the actual research papers?

4 - Which of the above treatments were you referring to in your
question? Again, my understanding is that the low-dose irradiation
delays ripening, but does not, in and of itself, prevent anthracnose
infections.  If I am misunderstanding this, please let me know.

5 - And finally, do you have a deadline for this? I ask because I will
be out of town all weekend and may not be able to get back to until
next week.

Let me know ?

-K~

Clarification of Question by phytosan-ga on 27 Nov 2003 06:15 PST
Thank you for your question. We are well aware of the benefits of
irradiation in insect desinfestation as this is our core bussiness.
Mango exporters in the world currently utilize hot water dipping to
control insects and as a secondary benefit this treatment also takes
care of anthracnose.

The cocnern of our customers is that when switching from hot water
dipping to irradiation for insect control, that they might see issues
with anthracnose surfacing.

We are talking about Mangifera indica L. and the information does not
need to be Mexico-specific.

We'd be very interested in hearing of combined treatment methods
involving irradiation not necessarily in the form of a research
report.

regards

Arved

Clarification of Question by phytosan-ga on 27 Nov 2003 06:18 PST
To some of your other questions: No specific deadline set. If you
provide an answer next week, that will work.

Industry reports will also be helpful

Arved
Answer  
Subject: Re: Irradiation Dose Necessary to Eliminate Anthracnose in Mexican Mango
Answered By: knowledge_seeker-ga on 28 Nov 2003 10:11 PST
 
Hi phytosan-ga,

I managed to find some time to work on this last night and this
morning, so I?m able to post your answer before I go.

I?ve done a thorough search of PubMed as well as an overall Google
search.  I found a number of articles, reports, and research papers
which all seem to corroborate each other when it comes to optimum and
safe irradiation doses for prevention of Anthracnose in Mangoes.

First is a summary of the data I found in all the literature and
sources I?ve provided later in my answer. I?ve pulled the irradiation
doses from each article to make it easier for you to compare them.

Next is some background which describes the development of Anthracnose
in ripening mangoes and then are the sources and links to either the
abstracts or the articles containing the actual data.

Where the link takes you to an abstract, I?ve indicated whether or not
the full text of the article is available for purchase online. In most
cases it is.

In some cases I?ve provided bibliographies of literature cited in the
articles. In these cases, the article cited was not available online,
but you may be able to follow up via your library.


Before we start -- a quick note on units (which I understand you may
already be aware of) ?

The unit of absorbed dose is the gray (Gy) where 1 gray is equivalent
to 1 joule per kilogram

1 Gray (Gy) = 100 rads
1 Kgy = 1000 Gray 
1 krad = 1000 rads

.25 kilograys = 25 kilorads



================
SUMMARY
================

FACTS
------

1 --- Colletotrichum gloeosporioides is the fungus that causes
      Anthracnose

2 --- The peel of an unripe mango contains antifungal chemicals that prevent
      the growth of Colletotrichum gloeosporioides

3 --- Irradiation delays ripening of Mangos, thus preventing
      anthracnose. 

4 --- Irradiation also sterilizes and controls insects



IRRADIATION DOSAGES CITED AS NECESSARY TO STERILIZE / CONTROL INSECTS.
----------------------------------------------------------------------

300 Gy control mango seed weevil 
150 Gy control 11 species of Tephritid fruitfly



IRRADIATION DOSAGES CITED AS NECESSARY TO DELAY RIPENING:
---------------------------------------------------------  

Low-dose UV irradiation protects against postharvest storage rots and
extends storage life, increasing resistance to fungal pathogens.

25 Krad extension in shelf life of 6 to 8 days at ambient temperature
25 Krad extension of storage life of about 10 days at ambient temperatures 
30 Krad causes ripening delay of 7 days at room temperature

0.25 kGy to 1.5 kGy in order to accommodate mangoes of various
varieties and different types of irradiators

0.25 - 0.75 kGy for shelf life extension (reports examined encompass 12 varieties)


Low doses (up to 1 kGy) delay physiological processes (ripening, etc.) 
Medium doses (1 to 10 kGy) extend the shelf life of commodities,
eliminate spoilage and pathogenic microorganisms, and improve the
technical properties of food.

3 minute exposure to infrared found to be as effective as the
commercially used five minute hot water treatment in controlling
anthracnose


COMBINATION OF IRRADIATION AND OTHER TREATMENTS CITED
-----------------------------------------------------

Hot water: 550 C for 5 minutes followed by 30 Gy 

TBZ, Benlate, Antracal and hot water dip alone and in combination with
gamma irradiation (300Gy)

Irradiation followed by hot benomyl treatment controls anthracnose



IRRADIATION LEVELS THAT CAUSE DAMAGE
------------------------------------

In excess of 600 Gy caused lenticel spotting, surface discolouration
and retardation.

Physical defects seem to be minimal up to a total overall average
absorbed dose of 0.60 kGy (maximum of approximately 1.0 kGy, assuming
a dose uniformity ratio of 1.2).?

Wholesomeness not affected by gamma-irradiation at a dose of 75 krd

30 Gy ? no radiation injury


DOSE UNIFORMITY
---------------

For mangoes - 650 Gray necessary to ensure a minimum dose of 300 gray throughout




===========
BACKGROUND
===========

?FAO estimated that over 23 million metric tons (MT) of mangos were
produced in 1998,about half of which were grown in India. Mexico,
however, is the world?s
largest exporter of fresh fruit; it shipped about 187,000 MT in 1997


??Mexican mangos have little or no anthracnose since they are produced
on the arid Pacific coast of that country. Thus, they are often
esthetically superior to Florida mangos.These factors, coupled with
low production costs in Mexico, have severely  crippled the Florida
mango industry.

?..Anthracnose is caused by, Colletotrichum gloeosporoides 

?..Infection may then proceed with the formation of infection pegs
from the base of the appressoria ?  this usually occurs, however, only
after fruits have begun to ripen.

?...the reason that these infections remain quiescent is not known,
but may be related to antifungal compounds that are found in the peel
of mango fruits?

Anthracnose: The Most Important Disease in Much of the Mango-producing World
http://plantpath.ifas.ufl.edu/Newsletter/Newsletters/Septmeber1999.PDF

------------------

Anthracnose. Caused by Colletotrichum gloesporioides, begins as latent
Disorders infections in unripe fruit and develops when the mangoes
begin to ripen. Lesions may remain limited to the skin or may invade
and darken the flesh.

UC DAVIS - POST HARVEST ? PRODUCE FACTS - MANGO
http://postharvest.ucdavis.edu/Produce/ProduceFacts/Fruit/mango.shtml

----------------------------------------

Antifungal Compounds and Fruit Ripening

?..The resistance of unripe fruits to fungal decay has been associated
with the presence of preformed antifungal compounds in the peel.
Pathogens often infect unripe fruits but then remain quiescent, with
the onset of decay coinciding with decreases in the concentrations of
antifungal compounds to subtoxic levels as the fruit ripens. Thus,
quiescence may represent a mechanism for avoiding toxic levels of
antifungal plant compounds. This area has been studied in particular
detail for interactions involving Colletotrichum gloeosporioides and
the subtropical fruits mango and avocado.

?..The peel of unripe mango fruit contains a mixture of the antifungal
5-alkylated resorcinols 5-12-cis-heptadecenyl resorcinol and
5-pentadecyl resorcinol (51), while avocado peel contains antifungal
monoenes and dienes (1-acetoxy-2,4-dihydroxy- n-heptadeca-16-ene and
1-acetoxy-2-hydroxy-4-oxo-heneicosa- 12,15-diene) (167, 168) (Fig. 7).

?..The levels of these compounds decrease during fruit ripening, and
this decrease occurs more rapidly in disease-susceptible cultivars,
suggesting that the presence of inhibitory levels of these antifungal
substances in the peel of unripe fruit may arrest fungal growth and
cause latency.

LIT CITED ABOVE

Droby, S., D. Prusky, G. Jacoby, and A. Goldman. 1986. Presence of
antifungal compounds in the peel of mango fruits and their relation to
latent infections of Alternaria alternata. Physiol. Mol. Plant Pathol.
29:173?183.




Fungal Resistance to Plant Antibiotics as a Mechanism of Pathogenesis
John p. Morrissey and Anne e. Osbourn*
MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS,
1092-2172/99/$04.0010
Sept. 1999, p. 708?724 Vol. 63, No. 3
http://www.jic.bbsrc.ac.uk/sainsbury-lab/anne-osbourn/mmbv1999.pdf



==============================================
ANTHRACNOSE ? IRRADIATION ? MANGOES - RESEARCH
===============================================

[abstract ? article available for online purchase]

?Three minute exposure to IR was found to be as effective as the
commercially used five minute hot water treatment in controlling
anthracnose (Colletotrichum gloeosporioides) and soft brown rot
(Nattrassia mangiferae) on seven mango cultivars??

SHORT WAVE INFRA-RED RADIATION AS AN ALTERNATIVE TO THE HOT WATER BATH
TO CONTROL POSTHARVEST DECAY IN MANGOES
http://www.actahort.org/books/455/455_98.htm

-----------------------------

?Extensive studies have been conducted to determine the effect of
r-radiation on the shelf life extension of mango.

The optimum radiation dose for Alphonso mango is 25 K rad, giving an
extension in shelf life of 6 to 8 days at ambient temperature.

A combination of hot water treatment (550 C for 5 minutes) followed by
30 Gy irradiation was found to be the best treatment in terms of shelf
life extension and quality of mangoes.

After this treatment, mangoes had a storage life of 38 days (at 150
C), 28% rotting and no irradiation injury.

It was observed that 300 Gy control mango seed weevil while 150 Gy was
shown to control 11 species of Tephritid fruitfly and 75 Gy prevents
the adults emerging from the fruits but more work is needed.

Doses of irradiation in excess of 600 Gy caused lenticel spotting,
surface discolouration and retardation of ripening of Kensington Pride
mangoes, but irradiation at this level contributed to only minor
improvements in disease control.

However, irradiation followed immediately by hot benomyl treatment
controlled anthracnose and stem-end rot during storage at 200 C for 15
days?

MANGO - Post Harvest Technology
http://www.ikisan.com/links/ap_mangoPost%20Harvest%20Technology.shtml


-----------------------------


[abstract only]

?It may be concluded that the wholesomeness of mangoes was not
affected by gamma-irradiation at a dose of 75 krd.?


The effects of low-dose gamma-irradiation on the wholesomeness of
mangoes (Mangifera indica) as determined by short-term feeding studies
using rats.
Br J Nutr. 1976 Jan;35(1):67-75.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1244845&dopt=Abstract

----------------------

Irradiation

Gamma irradiation (30 Krad) causes ripening delay of 7 days in mangoes
stored at room temperature. The irradiated fruits ripen normally and
show no adverse effect on quality. Irradiation has not yet been
approved for this purpose.

FAO REPORT - CHAPTER XX MANGO:  Post-harvest Operations
http://www.fao.org/inpho/compend/text/Ch20sec2_5.htm

-------------------

Pakistani Research on Use of Antifungal Treatments:

TBZ, Benlate, Antracal and hot water dip alone and in combination with
gamma irradiation (300Gy) were used to control the post harvest
problem of anthracnose and stem end rot in mangoes. However hot water
dip (55oC)highly significant to control this disease.

POST HARVEST HANDLING
http://www.telmedpak.com/agricultures.asp?a=agriculture&b=post_harvest

--------------------

Low-dose UV irradiation protects sweet pepper (1), mango (4), carrot
(43) and citrus fruits (49) against postharvest storage rots and
extends their storage life, increasing resistance to fungal pathogens.
However, it is necessary to study certain aspects of on-line
application of UV-C during fruit processing, including Phytoparasitica
26:1, 1998 61 factors such as fruit ripening and storage temperature
following treatment

Reference cited for above

Boulet, M., Arul, J., Verret, P. and Kane, O. (1989) Induced
resistance of stored mango (Mangifera indica L.) fruits to mold
infection by treatment with Colletotrichum gloeosporioides L. cell
wall hydrolysate. Can. Inst. Food Sci. Technol. J. 22:161-168.


The Postharvest Phase: Emerging Technologies for the Control of Fungal Diseases
M. Mari and M. Guizzardi (1998) Phytoparasitica 26(1):59-66
http://www.phytoparasitica.org/phyto/pdfs/1998/issue1/mar.pdf


--------------

[Abstract. Full text available for online purchase]

?Initial studies were carried out to ascertain the optimum radiation
dose required to delay ripening in the mango fruit.

Mature olive green Alphonso mangoes were irradiated in the
preclimacteric stage by 12, 25, 50, 75, 100 and 200 Krad. Optimum
radiation dose, as determined by maximum delaying effect and minimum
damage, was found to be 25 Krad and resulted in extension of storage
life of about 10 days at ambient temperatures (25?32C).?

Dharkar, S.D. and Sreenivasan, A. 1972. IRRADIATION AS A METHOD FOR
IMPROVED STORAGE AND TRANSPORTATION OF MANGOES. Acta Hort. (ISHS)
24:259-259
http://www.actahort.org/books/24/24_51.htm

---------------------------

All of the below from: 

HEALTH CANADA - IRRADIATION OF MANGOES:
http://www.hc-sc.gc.ca/food-aliment/fpi-ipa/e_mango_irradiate01.html


[page 1] http://www.hc-sc.gc.ca/food-aliment/fpi-ipa/e_mango_irradiate01.html
 
?The specific purpose of irradiation in the first submission is
disinfestation, specifically, to control fruit flies?..


[Page 2]  http://www.hc-sc.gc.ca/food-aliment/fpi-ipa/e_mango_irradiate02.html 


? The second submission is based on a request to be allowed "to extend
the shelf life of mangoes permitting the import and marketing of good
quality mangoes from tropical countries for the enjoyment of Canadian
consumers." The source of irradiation is Cobalt-60. The dose range
requested is 0.25 kGy to 1.5 kGy in order to accommodate mangoes of
various varieties and different types of irradiators (i.e. having
different dose uniformity ratios).


[page 4] http://www.hc-sc.gc.ca/food-aliment/fpi-ipa/e_mango_irradiate04.html

?With regard to physical alterations [of mangoes], the main one noted
is that higher doses than those required to delay ripening (i.e.
extend shelf-life) can result in scalding (surface browning or brown
spots) of the mango peel (skin). Optimal doses are variety-dependent
and, from Table 2 of the consultant?s review, seem to vary from 0.25 -
0.75 kGy for shelf life extension (reports examined encompass 12
varieties). Based on work undertaken on Haden, Keitt and Tommy Atkins
varieties, physical defects seem to be minimal up to a total overall
average absorbed dose of 0.60 kGy (maximum of approximately 1.0 kGy,
assuming a dose uniformity ratio of 1.2).?


-------------------

?The effects of irradiation depend on the dose absorbed. Low doses (up
to 1 kGy) inhibit sprouting in tuber, bulb and root vegetables,
inhibit the growth of asparagus and mushrooms, and delay physiological
processes (ripening, etc.) in such fruits as banana, mango, and
papaya. Medium doses (1 to 10 kGy) extend the shelf life of
commodities, eliminate spoilage and pathogenic microorganisms, and
improve the technical properties of food. Lastly, high doses (10 to 50
kGy) can be used for industrial sterilization and decontamination of
certain additives or ingredients (Morrison 1992, ICGFI 1994, OTA 1985,
Kader 1986)?

??Factors influencing the response of fresh fruits and vegetables to
irradiation include the type of commodity and cultivar, production
area and season, maturity at harvest, initial quality, and post
harvest handling procedures. Similarly, environmental conditions
during irradiation (temperature and atmospheric composition), and dose
rates are also influencing factors (ICGFI 1994, Kader 1986, OTA 1985,
Morrison 1992). The relative tolerances of fresh fruits and vegetables
to irradiation doses below 1 kGy are listed in Table 1 below.?

[mango not listed in Table 1]


US EPA: The Use of Irradiation for Post-Harvest and Quarantine Commodity Control*
http://www.epa.gov/spdpublc/mbr/casestudies/volume2/irad2.html

*Many offline references in that article. 


RELATED ARTICLE

The Use of Irradiation for Post-Harvest and Quarantine Commodity Control
http://www.epa.gov/spdpublc/mbr/casestudies/volume2/irad2.html

-------------------

[page 2]  ?..Studies have found that irradiation can have a number of
negative effects on this [Kensington Pride]  type of mango. Firstly at
overall doses as low as 100 gray the ripening process in the fruit is
halted. (The Australian mango is normally picked when it is still firm
and green in order to prevent the fruit being over-ripe when it
reaches markets). The irradiation process also results in effects on
the skin colouration of the fruit. Uneven colour spotting results and
pores on the surface of the fruit turn black, in addition the skin is
bronzed resulting in a mottled browning effect??

[page 3]  ?..The question of Dose Uniformity is particularly relevant
when dealing with fruits with hard kernels such as mangoes. A study
found that for mangoes a dose of 650 Gray was necessary to ensure a
minimum dose of 300 gray throughout.

??Besides the radiation source (E-Beams, Gamma Rays, X-Rays) there are
three important factors which affect the effectiveness of the
irradiation process. The distance of the food from the irradiation
source, the bulkiness of the food and its heterogenicity. It is of
concern that there is no detailed information in this application
regarding proposed procedure for irradiating these fruits. Important
points on which information is totally lacking are:

1. The distance of the fruits from the radiation source

2. Whether there will be a single radiation source or multiple

3. Whether there will be a single pass over the radiation source or multiple

4. If there is a single radiation source will the fruit be rotated or turned
   over to ensure even dosage on all surfaces, including the ends

5. How will the fruit be packed when it is irradiated - is it loose, in trays
   or in cases??


LITERATURE CITED


a. Rose, R.C. (1987), Ann.N.Y. Acad. Sci. 498, pp506-508 
b. Murray, David.R, ?Biology of Food Irradiation? Taunton, Somerset, England.
   Research Studies Press. 1990
c. Mathur, P.B., Lewis, N.F. ?Storage Behaviour of Gamma Irradiated Mangoes?
   Int. J. Appl.Radiat. Isot. ; IJARA; (1961); v.11. pp 43-45.


IRRADIATION OF TROPICAL FRUITS - BREADFRUIT, CARAMBOLA, CUSTARD APPLE,
LITCHI, LONGAN, MANGO, MANGOSTEEN, PAPAYA, AND RAMBUTAN.
http://www.sustainable.wellington.net.nz/Campaigns/Food_Irradiation_2002/Action%20for%20Environment%20Submission.pdf


====================================
LITERATURE CITED IN OTHER ARTICLES
====================================

These looked promising, but are not available online. 


SPALDING, DH & Reeder, W.f.  1986 Decay and acceptability of mangos
treated with combinations of hot water, imazil and gamma irradiation.
Plant Disease 70: 1149-1151

Upadhyay, IP, Noomhorm, A. & Ilangatile, S. 1994. Effects of gamma
irradiation and hot water treatment on the shelf life and quality of
Thai Mango cv. Rad. Pages 348-351 in: Postharvest handling of Tropical
fruits. Champ, BR. Highly, E.  & Johnson, GI. (Eds) Proceedings of an
international conference held at Chiang Mai, Thailand.

From: 

COMPARATIVE STUDY OF COLLETOTRICHUM GLOEOSPORIOIDES FROM AVOCADO AND MANGO
http://www.up.ac.za/academic/agrirural/mango/Pdfs/Thesis1999.pdf



So, that should give you everything you need. If anything I?ve said
isn?t clear, please feel free to ask for clarification.  As I
mentioned, I will be away for the weekend, but will respond when I
return next week.

Thanks so much for your question ?

-K~



==============
SEARCH TERMS
==============

PUBMED
http://www.ncbi.nlm.nih.gov/PubMed/




21 Search irradiation Mangifera 
#20 Search anthracnose Mangifera 
#19 Search anthracnose mango 
#17 Search anthracnose irradiation 
#16 Search gloeosporioides irradiation 
#15 Search gloeosporioides radiation 
#13 Search gloeosporioides mango 
#12 Search gloeosporioides gamma 
#11 Search Colletotrichum gloeosporioides gamma 
#9 Search Colletotrichum gloeosporioides radiation 
#8 Search Colletotrichum gloeosporioides irradiate 
#7 Search Colletotrichum gloeosporioides  
#5 Search Colletotrichum gloeosporioides mango  
#2 Search Colletotrichum gloeosporioides irradiation  
#1 Search Colletotrichum gloeosporioides irradiation mango 


Google
://www.google.com/webhp?hl=en


All of the above plus

mango irradiation dose
Mangifera indica mexico radiation

Request for Answer Clarification by phytosan-ga on 08 Dec 2003 15:09 PST
Thank you for a large amount of information. Unfortunately, the one
key piece of knowledge that we are looking for did not show up: What
is the dose of gamma irradiation necessary to eliminate Colletotrichum
gloeosporioides as the cause of Anthracnose in Mexican Mangoes.

Please narrow your search to this specific question.

Thanks

Arved

Clarification of Answer by knowledge_seeker-ga on 09 Dec 2003 07:23 PST
Hi phytosan,

I apologize for the confusion over your answer. Maybe I wasn?t clear
enough in my explanation.

You said:

||| The cocnern of our customers is that when switching from
||| hot water dipping to irradiation for insect control, that
||| they might see issues with anthracnose surfacing.?


This is indeed a valid concern. With gamma irradiation alone, although
you can postpone its growth, you will not be able to eliminate
Colletotrichum gloeosporioides. You will have to combine the gamma
radiation at doses between 25 and 30 Kilorads with hot water dip or
chemical treatment in order to do that.

As I mentioned in my Request for Clarification and in the Answer,
gamma radiation does NOT eliminate Colletotrichum gloeosporioides in
Mangoes.  It merely delays its growth by delaying ripening of the
fruit.

The fruit itself is naturally resistant to Colletotrichum
gloeosporioides until it is ripe. The gamma radiation delays ripening.
Once the fruit is ripe, it will be susceptible to infection by
Colletotrichum gloeosporioides unless chemicals or hot water are
employed to control the fungus.

In other words, you cannot eliminate Colletotrichum gloeosporioides as
a cause of Anthracnose by means of gamma radiation alone.

The radiation doses I presented in my summary are those doses that
various researchers have found to be effective in delaying ripening.
You can see that  doses of 25-30 kilorads (250-300 Gray) is optimal to
extend shelf life by 7-10 days.  This is approximately the same dose
that is recommended for insect control: 15-30 kilorads (150-300 Gray).

Studies show that increasing the dose does not improve the
effectiveness of the radiation. In fact, when exposed to doses
approaching 60 kilorads (600 Gray) the fruit becomes damaged.

To quote:

?Complete sterilization of fresh fruits is [impractical] because the
high gamma radiation doses required would damage important quality
attribution such as appearance, texture, taste and flavor. Most
attention has there fore been entered on the use of sub-sterilization
doses (pasteurization) Which inhibit physiological processes such as
sprouting, ripening and senescence.?

POST HARVEST HANDLING
http://www.telmedpak.com/agricultures.asp?a=agriculture&b=post_harvest


I hope I?ve been able to clear things up for you. I suspect that the
answer isn?t what you wanted to hear, but it is clearly what the
research is indicating.

Thank you for allowing me to clarify my answer.

-K~

Request for Answer Clarification by phytosan-ga on 12 Dec 2003 09:34 PST
Thanks for your clarification. Unfortunately I do not feel that my
question has been at this point, and that there is some confusion with
respect to the answer.

The cause of anthracnose is a fungus that like any other organsim that
has DNA can be eliminated with irradiation. The degree of elimination
is expressed in logarythmic reductions of any given organism and is a
function of dose measured in Gray. My specific question was, what this
dose might be for a given log reduction. Despite a large amount of
secondary information we did not get to the core of the issue.

The information of intrinsic imunity of unripe mango to anthracnose is
interesting but not entirely relevant.

Please let me know if you whish to investigate this further.

Thanks for a lot of work.

Arved

Clarification of Answer by knowledge_seeker-ga on 15 Dec 2003 06:11 PST
Hi arved,

I've enlisted the help of some other researchers. I'll get back to you
by Monday evening.

-K~

Clarification of Answer by knowledge_seeker-ga on 15 Dec 2003 15:06 PST
Hi again Arved, 

First my apologies.  Clearly my interpretation of your original
question and subsequent clarifications has led me down the wrong path.
I was working towards the amount of radiation commonly used as a
control. You wanted absolute levels without regard to normal accepted
usage or potential damage to the fruit.

I am certain, had you posed your original question in the way you
explained it in your final Request for Clarification, I wouldn?t have
attempted to answer it. What you are really looking for is outside of
my research comfort level.

In any case, I did rally some more qualified help this weekend and
spent quite a bit of time trying to find you some numbers.
Unfortunately, I was unable to come up with anything. I also alerted
the other researchers that I had hit an impasse with this, but none
were able to offer any assistance.

Since your question hasn?t been answered to your satisfaction and I
can?t improve on it, we?re at the point where we need to get you your
money back. If you go the link below there are refund instructions and
link to the refund form. Fill it out and the editors will decide
whether or not to grant the refund. (I have no control over that
part).

GOOGLE ANSWERS ? FAQ - REFUNDS
http://answers.google.com/answers/faq.html#refund

I see you have asked a number of questions here and have been
satisfied with your answers thus far.  I hope you continue to use
Google Answers.

Thank you for your patience.

-K~
Comments  
Subject: Re: Irradiation Dose Necessary to Eliminate Anthracnose in Mexican Mango
From: hlabadie-ga on 27 Nov 2003 05:09 PST
 
The only reference that I can find is to a dosage of 300 Gy (Grays),
but this appears to be in combination with other treatments.

hlabadie-ga
Subject: Re: Irradiation Dose Necessary to Eliminate Anthracnose in Mexican Mango
From: hlabadie-ga on 27 Nov 2003 06:24 PST
 
TelMedPak - Welcome to TelMedPak Agriculture
POST HARVEST HANDLING
http://www.telmedpak.com/agricultures.asp?a=agriculture&b=post_harvest

"Pakistani Research on Use of Antifungal Treatments:
TBZ, Benlate, Antracal and hot water dip alone and in combination with
gamma irradiation (300Gy) were used to control the post harvest
problem of anthracnose and stem end rot in mangoes. However hot water
dip (55oC)highly significant to control this disease."

hlabadie-ga

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at answers-support@google.com with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  


Google Home - Answers FAQ - Terms of Service - Privacy Policy