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Q: Effect of irradiation on Papaya ( Answered 2 out of 5 stars,   0 Comments )
Subject: Effect of irradiation on Papaya
Category: Science > Biology
Asked by: phytosan-ga
List Price: $50.00
Posted: 21 Apr 2004 18:11 PDT
Expires: 21 May 2004 18:11 PDT
Question ID: 334083
PHYTOSAN S.A. de C.V. ( is a company that is
constructing phytosanitary irradiation facilities in Mexico mainly to
help keep the Mexican fruit fly from spreading into the north of the
country. We have been approached by customer groups who would like to
use the technology to eliminate anthracnose and other fungus deseases
that limit shelf life in Mexican papaya. At this point we are
interested in an overview of the effects of low dose irradiation on
common Papaya deseases and a
recommended dose to handle anthracnose and optimize shelf life.

Arved Deecke
phytosan S.A. de C.V.
Subject: Re: Effect of irradiation on Papaya
Answered By: adiloren-ga on 22 Apr 2004 17:17 PDT
Rated:2 out of 5 stars
Hi, thank you for your question.

The literature on irradiation shows that it is approved almost
worldwide in low doses for tropical fruits like papaya, as well as
some meats for preserving shelf life and eradicating certain diseases
common to them. I have provided you with an overview of the literature

This article refers to the specific ammount of irradiation safe to
consumers and even refers specifically to papayas.

Food & Pack (Australia)
June 2002
HEADLINE: ANZFA votes food irradiation safe

To date, Australians have not come face-to-face with irradiated
produce, as irradiation of food was banned in Australia up until 1999.
From this date, approval has been sought from ANZFA on a case-by-case

The application from Surebeam Australia to irradiate tropical fruit is
the second proposal concerning irradiation ANZFA has put forward for
public comment since 1999. Construction is about to start on a herb,
spices and herbal infusion plant at Naranga, North of Brisbane, the
result of the first successful application to ANZFA in 2001.

Steritech's Narangba plant will use Cobalt-60 rods producing gamma
rays to irradiate its produce, while Surebeam's application proposes
to use electronic beam technology from commercially available
electricity to eradicate pests like fruitfly on specific tropical
fruits including breadfruit, carambola, litchi, longan, rambutan,
lychee, mango, papaya and custard apples.

Irradiation involves eradicating bacteria, mould, insects and other
pests through the use of gamma rays, electrical beams or X-rays.

This is done as an alternative to using chemical fumigants,
pesticides, hot water dipping, and refrigeration, and works by
disrupting the organic processes that lead to food spoilage and decay.

Food irradiation is currently common practice in Europe and the US
where consumers are more concerned about the dangers of food-borne
diseases like e-coli and BSE than possible nutritional loss due to the
irradiation process.

Commenting on Australian consumer perceptions, Dr Roger Harker,
scientist at New Zealand's HortResearch, said: "It eventually comes
down to whether you trust science or not. I think it is almost
incomprehensible that technology as safe as irradiation is rejected
for so long and within the timeframe that many other technologies like
microwaves and cell phones have become part of everyday life."

ANZFA has concluded that the irradiation of tropical fruits to a
maximum of one kilogray from machine-sourced electron beams or x-rays,
employing "Good Manufacturing/Irradiation Practices", is safe for

ANZFA commented: "In the context of an overall diet, the irradiation
of the fruits would have a minimal impact on an individual's nutrient
intake. If permitted, irradiated tropical fruits would require
mandatory labelling to give consumers an informed choice when buying
these fruits."

Some consumer groups do not agree with ANZFA's assessments, and there
have been ongoing protests at the Narangba site.

Concerns over the process centre around fears that the nutritional
value of irradiated products is decreased.

Friends of the Earth irradiation spokeswoman Rebecca Duffy said
reasons given for food irradiation did not stack up, and that simpler,
age-old techniques using better food-handling practices were just as

She suggested that locally grown, locally processed and locally
distributed food would reduce the need for irradiation.

ANZFA's recommendation on tropical fruit irradiation still remains
subject to public consultation. Its findings refer to seven countries,
including the USA and UK, where the irradiation of fruits for
quarantine reasons is commonplace.

On irradiation:

"This alternative provides agency programs with another regulatory
treatment method for phytosanitary certification of fruits and
vegetables for import, interstate movement, and export. The use of
irradiation treatment does not replace the other available regulatory
treatments, but provides another regulatory option. Under this
alternative, the other treatments from the limited no action
alternative would continue to be available and would continue to be
used for regulatory purposes. The addition of irradiation regulatory
treatments to the treatment schedule for fruits and vegetables could
diminish the dependence on some of the other treatments. Although
irradiation treatments have been found to effectively control many
pests, the high cost of setting up an irradiation facility makes it
likely that only a few larger facilities will actually seek
certification from APHIS to use this technique. The use of irradiation
treatment for phytosanitary purposes could expand with the anticipated
increases in import and export of various fruits and vegetables
resulting from the continuing development of new trade agreements." 

With some foods, even the best sanitation and standard antibacterial
treatments cannot ensure safety. For example, there is no guarantee
that raw ground beef or raw sprouts will be free of certain harmful
bacteria. These foods provide a favorable environment for bacterial
growth and their production process does not include a “kill step,”
such as cooking or pasteurization. For these foods, irradiation
provides a “bacteria-killing” step without cooking the food. Foods may
also be irradiated to extend shelf life, and imported fruits and
vegetables may be irradiated to kill insect pests that might otherwise
threaten U.S. agriculture. 

There are several benefits of expanding the use of irradiation
treatments to control pests infesting perishable and non-perishable
commodities in the United States. First, irradiation may be useful for
preventing the movement of quarantine species possibly present in
trade commodities into areas where such pests are not established
(USDA 1996b). From an economic standpoint, irradiation, therefore, has
the potential to increase trade opportunities between nations,
especially from major fruit and vegetable producing countries with
high infestation rates (ICGFI 1994). Irradiation also can be used to
reduce the risk of infection and disease caused by foodborne pathogens
(Moy 1991). Although consumers have concerns associated with the
safety of irradiation technology and its effects on food,
dartsdelight: research indicates that properly irradiated food does
not pose a risk to consumers (Thorne 1983, OTA 1985). In fact, the
potential for human health impacts from exposure to foodborne
pathogens is believed to be substantially reduced through the use of
irradiation (OTA 1985, Morrison et al. 1992). 

advantages in applying irradiation to food industry.  Long-term safe
storage of food resources by eliminating parasites and contaminated
organisms, and following improvement of efficiency and cost stability
of agricultural products.  Prevent food-borne diseases by
eliminating pathogenic microorganisms in food products and
substitutional use for chemical preservatives.  Is an effective
method for quarantine management closely related to public health. 
Is an alternative for conventional food processing method and can be a
method for developing new products. Health authorities in many
countries have introduced stricter hygienic standards in food trade.
dartsdelight: Such standards often mandate zero tolerance of pathogens
such as Salmonella and Vibrio cholerae in imported food products. The
U. S., for example, has already introduced zero tolerance for L.
monocytogenes in ready-to-eat food in trade. All countries aim
nowadays is to ensure the common safety by satisfying the standards
other countries in safety aspects either biologically or chemically. 

Food irradiation is one means of food preservation that may not be
familiar to many, but it has been in development since the early
decades of the twentieth century. If properly applied, irradiation can
be an effective way to treat a variety of problems in our food supply,
such as insect infestation of grains, sprouting of potatoes, rapid
ripening of fruits and bacterial growth. 

Although the US food supply has achieved a high level of safety,
bacterial hazards still exist in our food. The US Center for Disease
Control estimates that 76 million cases of foodborne illnesses occur
every year. They also estimate that one in four Americans gets a
foodborne illness each year. 

Nuclear News
July, 2003
HEADLINE: Irradiated food, good; foodborne pathogens, bad

TO HUNDREDS IN the audience, Elsa Murano explained how the federal
government decides to approve methods for food decontamination. Those
decisions are always based on whether a technology is safe and
effective. "Irradiation meets both of these criteria," said Murano,
undersecretary for the Food Safety and Inspection Service (FSIS) of
the U.S. Department of Agriculture (USDA). "Irradiation has been
approved by the Food and Drug Administration [FDA] for meat and
poultry as well as for a variety of other foods. Irradiation has been
endorsed and supported by many highly respected public health
organizations, including the Centers for Disease Control and
Prevention [CDC], the American Medical Association, and the World
Health Organization [WHO]. In fact, it is one of the most thoroughly
researched processes in existence."

On anthracnose:

The Hindu
July 1, 1999

Infection anthracnose and red rust starts on leaves and fruits of
late-maturing varieties owing to increase in humidity. The spots due
to anthracnose are round, small and necrotic, whereas in red rust
pink-red velvety and irregular growth develops. Spraying of copper
oxychloride 3 g/litre water during third or fourth week takes care of
both diseases.

The rots caused by Sclerotium and Rhizoctonia species may spoil
seedlings in nursery. Therefore sterilising the soil with formaldehyde
and then covering with polythene is quite essential. Remove polythene
and keep the soil open so that leftover formaldehyde is evaporated.

Mango stones should also be treated with Thiram or Captain (3 g/litre
water) for 5-10 minutes. By doing this there is no chance of rotting
of mango stones. More seedlings are obtained.


Second and third sprays of copper oxychloride (0.3 per cent) at 15-20
days should be done to protect the crop from anthracnose and red rust.
If some seedlings are affected by rotting, treat the field with Captan
(0.3 per cent). God drainage facility should be maintained in nursery.
Weed out all grasses etc. to remove the collateral hosts of
Slerotonium and Rhizoctonia species.


If anthracnose or red rust are not under control, repeat one more
spray of copper oxychloride. Clean the field by ploughing deeply as it
reduces several pathogens.


The incidence of die-back, phoma blight and gummosis increases by this
time. Prune infected and dried branches to control die-back in nursery
as well. After pruning apply copper oxychloride paste to the cut ends
in nursery, whereas on grown up plants spraying of copper oxychloride
(0.3 per cent) is recommended.

Spraying of copper oxychloride (3 g/litre water) controls small light
brown spots of irregular to larger irregular spots of phoma blight.
Similarly gummosis may be controlled by spraying copper oxychloride
(0.3 per cent).

Apply 200-400 g of copper sulphate near the feeding root zone of every
mango plant. Other necessary fertilisers should also be applied during
October. It helps develop the vigour of the plants.

Spraying of NAA 200 ppm up to mid-October is quite necessary to keep
malformation diseases under control.

Grounds Maintenance
July 1998
HEADLINE: Managing Resistance --Part I: Fungicides

Site-specific fungicides, better known as systemic fungicides, are vital
tools for turfgrass managers. Their effectiveness and length of control are
superior to that of contacts, so they have become important tools for
managing disease in high-quality turfgrass. However, systemics have
increased the problem of resistance because fungal pathogens more easily
tolerate site-specific fungicides, which primarily act on just one
physiological mechanism in the fungus. Contact fungicides, though they
offer shorter and, in some respects, inferior control, typically affect
several sites in the fungus. Therefore, it's more difficult for fungi to
develop resistance to contacts. That's why the resistance problems we know
of almost entirely involve systemic fungicides.

The most significant problem with resistance to systemic fungicides is with
Sclerotinia homoeocarpa, the cause of dollar spot. The other pathogen with
which resistance occurs frequently is Microdochium nivale, the cause of
Microdochium patch. Resistance to systemic fungicides by Pythium
aphanidermatum, a cause of pythium blight, and by Colletotrichum
graminicola, the cause of foliar and crown-rotting anthracnose, also occur
but much less frequently. 

The three major fungicide groups to which resistant strains of S.
homoeocarpa have developed are the benzimidazoles, dicarboxamides and the
demethylation inhibitors (DMIs). We have even found strains of S.
homoeocarpa with resistance to all three chemistries, which beckons the
question: How did strains with resistance to all three chemistries develop
on the golf course? The answer is quite simple: The golf-course
superintendent rotated all of the different chemistries into his fungicide
program, just as he was told to do to prevent resistance from occurring.
This would have worked fine had the individual strains of S. homoeocarpa
been able to accumulate resistance to only one fungicide. However, we now
know that strains of S. homoeocarpa can accumulate resistance genes to at
least three different chemistries. Therefore, alternating systemic
fungicides with different modes of action will not prevent resistance from
developing. It will only produce strains of S. homoeocarpa resistant to
whatever chemistries you put into the rotation.

I hope that we can eliminate from our vocabulary the phrase, "You should
practice good fungicide-resistance management and rotate fungicides with
different modes of action." Alternating different chemistries will only
select for strains with multiple resistance to whatever chemistries you use
in the rotation. You actually would be better off using one site-specific
chemistry for the control of dollar spot until resistance develops, then
switching to a product with a different mode of action.

For example, if it takes 5 years for S. homoeocarpa to develop resistance
to fungicide X and 5 years to develop resistance to fungicide Y, then using
fungicide X for 5 years and then switching to fungicide Y should give you
10 years of dollar-spot control. However, alternating fungicide X with
fungicide Y will give you resistance to both fungicides, often in less than
10 years, because S. homoeocarpa strains exist in the population with
resistance to both chemistries. You actually could lose several years of
dollar-spot control that you could have had by using the two fungicides

Other practices help extend the effective life of fungicides. These include
scouting and only applying a systemic fungicide when dollar spot has
reached a certain threshold level or alternating with a contact fungicide.
These techniques delay the development of resistance by reducing the number
of fungicide applications you make with the systemic fungicides. This
increases the number of years it will take to reach the critical number of
applications necessary for resistant strains to become dominant in the
population (see table, page 18).

Conventional wisdom has been to alternate systemics with contact fungicides
or combine a systemic fungicide with a contact fungicide. This way, as the
thinking goes, the contact fungicide will eliminate resistant individuals
that the systemic does not kill. The reason this doesn't work (in the way
people think it does) is that the contact cannot differentiate between the
resistant strain and the wild types-it works equally well on both. If it
cannot tell them apart, how is it going to eliminate one and leave the
other? In other words, the contact will not alter the ratio of resistant
types to wild types. Conversely, the systemic fungicide can only eliminate
the susceptible wild types from the population because the other strains
are resistant to it. Thus, the proportion of resistant types in the
population will increase due to selection by the systemic, while the
contact remains essentially neutral in its effects on the composition of
the population. Therefore, the benefit of including a contact fungicide is
not to eliminate the resistant strain (which it will not do) but to reduce
the number of systemic applications you make in any one year. This extends
the number of years you can use the systemic fungicide, but it does not
prevent the eventual development of resistance.

The fact that strains of S. homoeocarpa with resistance to three fungicide
groups exist invalidates the theory that alternating different fungicide
groups prevents resistance from occurring. You should use one class of
chemistry to manage dollar spot until resistance occurs. Do this in
conjunction with good integrated-disease-management practices and the use
of contact fungicides to prolong the useful life of the systemic fungicide.
Remember, contact fungicides will not eliminate resistant strains; they
merely extend the life of site-specific fungicides by delaying the time it
takes to reach the critical number of applications necessary for resistant
strains to become dominant.

Dr. Joseph Vargas is professor of plant pathology at Michigan State
Univeristy (East Lansing, Mich.).

The Monitor (Uganda) - AAGM
March 23, 2004

A UK standards body has approved the use of a pesticide that treats a
ginger fungal disease, which hit the crop last year.

Cupocassaro (cooper-ox chloride) was last year used to treat
anthracnose, a fungal disease, which had destroyed ginger gardens.

The Institute of Market Ecology (IMO) a certifying body approved
cupocassaro as the right organic pesticide to treat the fungal

"The disease (was) on for the whole of last year (and) in the month of
November there was no single ginger for export," said Ms Sonia
Mwadime, the operations manager Amfri Farms Ltd.

Five major farmers in Mpigi district were badly affected and had to
burn their fields.

This impacted on the price of ginger falling from Shs 2,000 to Shs 500
per kilogramme.

The pesticide, however, is not on the Agro Chemical Board's list of
chemicals to be used in Uganda; it is not available on the local

Amfri Farms imported only 74 kilogrammes of the pesticide from Kenya
at a cost of KShs 250 (Shs 6,000) per kilogramme.

Mwadime said that this is still little because an acre uses up 12-15
kilogrammes of the pesticide.

UK companies like that of Prince Charles; 'Dutch Originals' placed
orders for ginger but nothing was delivered after the disease ruined
the crop.

Mwadime said that only 50 tonnes of ginger were exported last year to
German, the UK, and Holland.

Meanwhile the trial shipment of more than 20 types of fresh
commodities to a direct seller in Holland is yielding success.

Mr Amin Shivji, the managing director Amfri Farms, said that hot
pepper, matooke, and apple banana have attracted the new market.

On January 27 Amfri Farms shipped one tonnes of 20 different fresh
commodities to Holland after getting a direct seller Mr David Kirunda.

Kirunda, a Dutch-based businessman, sold the commodities on behalf of
Amfri cutting out middlemen.

The commodities included pineapples, matooke, sweet potatoes,
sugarcane, okra, hot pepper, dried fruits, garden egg, avocado,
dhudhi, apple banana, passion fruits, mangoes, cocoyam, chillies,
cassava, tilapia and sweet pepper.

Distributed by AllAfrica Global Media. (

The Hindu
April 19, 2001

THE INDIAN Agricultural Research Institute (IARI), New Delhi, has
developed a high yielding grape variety, which is ideal for making
juice and coloured wine making. The improved variety called, "Pusa
Navrang" has bluish berries, and both the skin as well as the pulp has
distinct colouration, according to the scientists who developed this
variety."Pusa Navrang" is early ripening type, and it is resistant to
anthracnose disease. It is basal bearing in habit. Its berries contain
up to 90 per cent edible portion, 80 per cent juice and 17 per cent
total soluble solids. Its juice can be used as a colour additive for
making fruit and vegetable juices and also for blending with juice
extracted from white varieties of grapes, according to scientists.

Grape is one of the promising horticultural crops. This highly
remunerative crop needs high initial investment as well. The vines are
vegetatively propagated, and trained on "pandal" or bower. Grapes can
be grown in well-drained soil of neutral pH ranging between 6.5 to
7.5. In well-endowed red and black loamy soils, the crop grows
luxuriously.Grape requires a warm and dry weather. Cloudy weather,
high humidity, low temperature and rains during flowering and berry
development are not desirable as they are congenial to the spread of
diseases, say horticulturists. A spacing of 3 m by 3 m is normally
recommended for high yielding varieties, and about 1,112 plants will
be needed to cover a hectare.

The crop responds well to regular manuring and copious irrigation.
Adequate plant protection measures should be taken to raise a crop in
a healthy state.

A number of diseases attack this crop, and care should be taken to
ward off the diseases. The crop needs proper training, and periodic
pruning. By regular pruning the excessive vegetative growth is
curtailed, and the formation of fruitful bud is induced.

The vineyard should be kept absolutely free from weeds. Shallow
digging once in two to three weeks should eliminate all the unwanted

The weeding is best done with spade by manual labour. The size and
quality of the bunches can be improved by spraying with some growth
regulators such as gibberelic acid at the time of flowering and berry

The bunches can also be dipped in solutions containing the growth
promoting substances. This would ensure bigger berries and higher
yield, according to experts.

The ripe bunches have to be harvested carefully without causing any
damage to berries and packed well in cardboard cartons or bamboo

The bunches are to be cut with secatures or a pair of scissors, and
immature and rotten berries should be removed with a pair of scissors.
Paper strips should be used to avoid damage to the berries.

October 10, 2000
HEADLINE: PRESS RELEASE: Georgia's strawberry growers temporarily
cleared to use Quadris fungicide, announces Georgia Agriculture
Commissioner Tommy Irvin

Georgia Agriculture Commissioner, Tommy Irvin, announced that
Georgia's strawberry growers have been temporarily cleared to use the
fungicide Quadris to control anthracnose.

The temporary clearance comes as a result of Commissioner Irvin's
appeal to the US Environmental Protection Agency for an emergency
exemption for the strawberry growers.

According to the Commissioner, using Quadris could result in a 40%
greater marketable yield than using some of the lesser effective
chemicals on anthracnose.

Out of the 300 acres of strawberries in Georgia the average losses due
to anthracnose is 15%/y, which amounts to $402,000.

Growers will be able to use the fungicide Quadris through 30 Jun 2001.

Georgia Department of Agriculture, USA, Tel: +1 404 656 3689, Fax: 404
656 9380Newswire

November 19, 1997

The Indian coffee industry which earns foreign exchange of Rs 15
billion (US$ 414 million) annually is under severe threat from scores
of fungal diseases.

Leaf rust, Black rot, Pink disease, Anthracnose, Root rots, Berry
blotch, Brown-eye-spot and Collar rot are the most dreaded diseases
hitting the coffee plantations, according to eminent agriculture
scientist Dr R Naidu.

The director (research) of the Central Coffee Research Institute, in
the southern Indian state of Kerala, has carried out extensive
research work in the disease cycle of important coffee disease causing
pathogens and found that minor diseases like Grey blight, Black leaf,
Target Leaf spot, Tip blight, Coffee blight and Soft rot also take
their toll at relatively lower scales.

Among the two commercially cultivated species, Arabica (Coffea
arabica) is more susceptible than Robusta (Coffea canephora), Naidu

Each part of the coffee plant -- leaves, branches, roots, berries and
seeds -- is affected by fungal pathogens causing considerable economic
loss, he said.

Western Farm Press
August 18, 2001
HEADLINE: Anthracnose studies advance integrated control program;

Continuing studies supported by the California Lettuce ResearchBoard
are accumulating data for development of an integrateddisease
management program for anthracnose, which struck CentralCoast fields
for a time this spring.

Steve Koike, Monterey County farm advisor, said outbreaks of
thedisease, which produces lesions on inner leaves of romaine and
leaflettuce, were severe in some fields from late March until early
Mayand associated with cool temperatures and rain.

"It was more severe in the Santa Maria area and low tomoderate around
Salinas, it eased up when the rains stopped, and ithad disappeared by
May," he said.

Frank Laemmlen, Santa Barbara County farm advisor, said thedisease was
found in many heads in the Santa Maria area, causingthe stripping down
of heads and in some cases abandonment offields.

Noting that Quadris is approved for use against the disease onlettuce,
Laemmlen said treatments must be made preventively, sinceprophylactic
applications to do not prevent lesion formation andhead loss.

Anthracnose, also known as ringspot and shothole, is caused
byMicrodochiuim panattonianum, a soil-borne fungus. Koike recalled
itwas particularly severe and prolonged during the 1998 "ElNino"
spring, but infections have been comparatively mildsince.

The CLRB has allocated funds for compiling research data onrefined
spray fungicide application programs, detection, how thedisease
develops, and tests for cultivars having resistance. Thiswill be used
for an integrated program to manage the disease.

Due to moderate rainfall and comparatively light pressure fromthe
disease this year and the preceding two seasons, Koike'sresearch
plots, which were poised for any outbreak, had little toshow.

Survive in soil

Ring spot occurs in most cultivars of lettuce, and romaine
isparticularly sensitive to it. It has the ability to survive in
soilfor as many as four years without a lettuce host.

It is conveyed by water from sprinklers or rain splashing fromthe soil
onto lettuce leaves. Another source of inoculum can bediseased,
undecomposed lettuce crop residue.

Koike said studies on the fungus at the University ofCalifornia, Davis
showed it has at least five races of varyingseverity against lettuce.
Field and greenhouse trials demonstratedthat Folicur and Quadris
effectively control the disease.

Laemmlen said varnish spot disease also caused more losses thanusual
in lettuce during the spring. The disease, caused byPseudomonas
cichorii, may not show symptoms until near harvesttimewhen several
leaves of a head have shiny black necrotic spots,freckles, or

Little is known about how it spreads, but varnish spot isassociated
with sprinkler irrigation or rains. Other than avoidingsprinkling
lettuce after thinning, no management strategies areknown at this
time, Laemmlen said.

PR Newswire
July 18, 2000, Tuesday
HEADLINE: Demegen Announces Resistance to Three Important Plant Fungal
Diseases in Tobacco and Cotton Plants

Demegen, Inc. (OTC Bulletin Board: DBOT), announced today that
scientists at the USDA have produced tobacco and cotton transgenic
plants which express a gene encoding a novel antimicrobial peptide and
show high levels of resistance against three important fungal
pathogens.  Dr. Jesse Jaynes, Vice President of Research at Demegen,
designed the synthetic peptide, D4E1, which has a broad spectrum
activity against several bacteria and fungal phytopathogens.  Patents
assigned or licensed to Demegen cover this technology.  In addition to
Dr. Jaynes, the research team included Doctors Jeffrey Cary, Kanniah
Rajasekaran, and Thomas Cleveland from the Food and Feed Safety
Research Unit of the USDA Agricultural Research Service Southern
Regional Research Center at New Orleans, LA. Results of this work were
recently presented at the 6th International Congress of Plant
Molecular Biology held in Quebec, Canada in June and published in the
May 2000 issue of "Plant Science."
    The scientists reported that transgenic tobacco plants
demonstrated a significant reduction in anthracnose severity caused by
the tobacco pathogen Collectotrichum destructivum.  Also crude protein
extracts from leaf tissue of these plants reduced the germination of
conidia of the fungus Aspergillus flavus by 75% and the wilt fungus
Verticillium dahliae by 99%.  Preliminary results from a parallel
experiment with immature cottonseeds from transformed cotton plants
showed a similar inhibition in vitro of germinated conidia of A.
flavus and V. dahliae.  A. flavus produces aflatoxin, a deadly
carcinogen, in several economically important crop plants such as
cotton, peanut, corn and tree nuts compromising food and feed safety.
    Richard Ekstrom, President of Demegen, commented: "Fungal diseases
are a major problem, not only for farmers, but also for consumers when
these toxins enter the food chain.  We believe this novel peptide
invented by Dr. Jaynes can be a significant tool in combating fungal
diseases.  We are looking forward to extending this research into
other important crops."
    Demegen, Inc. is a research & development company that designs and
develops novel peptides and genes to improve the health of humans,
animals, and plants.  Building upon interconnected technology
platforms, the Company has both pharmaceutical and agricultural
products in development.  The medical applications include preventing
or treating cancers and infectious diseases. The agricultural
applications include plants that have enhanced fungal and bacterial
resistance and plants with improved protein quality and quantity.
Demegen's web site is

Forward-looking statements in this release are made pursuant to the
"safe harbor" provisions of the Private Securities Litigation Reform
Act of 1995. Investors are cautioned that such forward-looking
statements involve risks and uncertainties, including but not limited
to, results of research and development, the U.S. Food and Drug
Administration and other regulatory agencies, increased competition,
product development and commercialization, and other risks detailed
from time to time in the Company's reports filed with the Securities
and Exchange Commission.

Additional Links

Grounds Maintenance, March 1, 2004, ISSN: 0017-4688; Pg. 3, 2797
words, Understanding Fungicides, By Henry T. Wilkinson, University of
Illinois & Randall T. Kane, Chicago Golf District Association

CHEMICAL NEWS: Captan 50 WP: 24(c) fungicide label to use on two

Soybean Digest, October 1999, ISSN: 0038-6014 , 569 words, Anthracnose
Poses Double Threat, Kate Fisher

MONTEREY COUNTY HERALD, December 7, 1998, Monday, MN-FUNGUS, 900
words, Fungus Hits Lettuce in Salinas Valley, Calif., By Betsy Lordan

Search Strategy

Google search terms:
papaya "low irradiation dose"
anthracnose and irradiation
And used additional terms to narrow the field

Thanks again for your question. I will be happy to clarify if
necessary. Hope this helps.

Anthony (adilorenga)

Request for Answer Clarification by phytosan-ga on 26 Apr 2004 08:01 PDT
Thank you for a lot of information and a lot of work that you put into
your answer. Unfortunately your answer is much to general to be useful
for us. We are in the irradiation industry and know all regulatory and
consumer acceptance issues.

Please narrow your answer to issues specific to the irradiation of papaya.


Arved Deecke

Clarification of Answer by adiloren-ga on 26 Apr 2004 11:28 PDT
Hi, I apologize if the information was too general for your needs. I
extensively searched the web and lexis for specific information to
papayas, but didn't come up with much. I figured that you could still
employ the inforamation I provided on tropical fruits. I have tried
some new search strategies and found a few new sites and articles that
may be more useful. Here is what I've found:

* The maximum irradiation dose for papaya in Mexico is 2.50 KGy and in
the United States, it's 1.00 KGy:  (go to database and then search by food, ie. papaya)

"MEXICO 5 UNCONDITIONAL 07.04.95 2.50" (KGy)  
"USA  1,2 UNCONDITIONAL 18.04.86 1.00" (KGy) 

* The Internaltional Consultive Group on Food Irradiation website
seems to be valuable:

* According to this document, shelf life can indeed be extended,
through irradiation, for papaya:

by O.P. Snyder and D.M. Poland; Copyright 1995
Hospitality Institute of Technology and Management St. Paul, MInnesota

"Not all fresh produce is suitable for irradiation. The shelf life of
mushrooms, potatoes, tomatoes, onions, mangoes, papayas, bananas,
apricots, strawberries, and figs can be extended with low-dose
irradiation with no loss in quality. However, the quality of some
foods (some citrus fruits, avocados, pears, cantaloupes, and plums) is
actually degraded by irradiation."

* This document provides specic dosage levels and refers to tropical
fruits and papaya specifically at one point:
Animal and Plant Health Inspection Service
7 CFR Parts 305 and 319     [Docket No. 98-030-1]   RIN 0579-AA97
Irradiation Phytosanitary Treatment of Imported Fruits and
AGENCY: Animal and Plant Health Inspection Service, USDA.
ACTION: Proposed rule.

"The first calculated estimates of doses to provide probit 9
security against fruit fly adult emergence were made by Balock et al.
(1966). The probit 9 estimate of the irradiation dose that would
prevent the emergence from fruit of adult Oriental fruit fly,
Bactrocera dorsalis (Hendel), varied from 206 Gray in papaya to 280
Gray in a combination of eight different

*Another irradiation dose level reccomendation in regard to papaya specifically:

[Federal Register: February 5, 2003 (Volume 68, Number 24)]
[Rules and Regulations]               
[Page 5796-5800]
From the Federal Register Online via GPO Access []
Animal and Plant Health Inspection Service
7 CFR Part 318
[Docket No. 00-052-2]

"...abiu, atemoya, carambola, litchi, longan, papaya, rambutan, and
sapodilla to be moved interstate from ... had proposed a minimum
ionizing irradiation dose of 250 Gy..."

*A document from the Australia-New Zealand Food Authority on the
irradiation of tropical fruits, including specific dosages (PDF

Application A443
Irradiation or Tropical Fruits- Breadfruit, Carambola, Custard Apple,
Litchi, Longan, Mango, Magosteen, PAPAYA and Rumbitan

* This is a document on the irradiation of mangoes, but it includes
the excerpted information on doses for papaya as well:

Health Canada
Summary of Submission Process

?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)"

* Article on Irradiation that includes a table of recommended dosages
for different types of foods:

Access Science
Food irradiation;

"Fruits and vegetables FDA 1986 max. 1.0 KGY - Insect disinfestation;
maturation delay"

"Irradiation can be used for fruits and vegetables to prevent
overripening or sprouting as well as to eliminate infesting insects
and microorganisms. In Japan, which bans chemical sprout inhibitors,
potatoes are irradiated on a commercial scale to ensure availability
throughout the year. In the United States, fruits from Hawaii can now
be marketed in other states provided that they are irradiated to
disinfest them of fruit flies, including the Medfly. An especially
successful application is the irradiation of strawberries to prevent
mold formation and to extend the refrigerated storage time to about 3
weeks. Mushrooms have also been irradiated."

* Another U.S. government document on papaya irradiation doses:

[Code of Federal Regulations]
[Title 7, Volume 5]
[Revised as of January 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 7CFR318.13-4f]

"Approved irradiation treatment. Irradiation, carried out in 
accordance with the provisions of this section, is approved as a 
treatment for the following fruits and vegetables: Abiu, atemoya, 
carambola, litchi, longan, papaya, rambutan, and sapodilla."

General provisions for food irradiation
[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR179.25]

* Discussion of 2-DCB and Palmitic Acid: (may be related to irradiation in papaya)

"Numerous studies conducted since 1990 have identified 2-DCB as a
unique irradiation byproduct of palmitic acid at doses as low as 0.5
kGy.[10] These studies have identified 2-DCB in numerous types of
food, including beef, pork, lamb, chicken, eggs, mangoes, papayas,
cheese, and freshwater, seawater and anadromous fish.[11], [12] In
fact, 2-DCB, which has never been found in any non-irradiated
food,[13] is so readily identifiable as a unique irradiation byproduct
of palmitic acid that it is commonly used as a marker for irradiated
food  a byproduct that has been shown to persist in food up to 13

Palmitic acid is ubiquitous in foods, appearing in pronounced
quantities in virtually all types of meat (including fish and
shellfish), vegetables, fruit, grains, dairy products and vegetable
oils.[15] Palmitic acid also appears in pronounced quantities in
dozens of ready-to-eat foods, including sauces, pizzas, baked goods,
snack foods and many other types of food.[16"

* Maybe a bit off topic- but I thought you may be interested in this:

Food irradiation  
J Am Diet Assoc. 2000;100:246-253

"Consumer performance in the marketplace supports the results of
attitudinal surveys (27). Mangoes labeled as irradiated sold
successfully in Florida in 1986. In March 1987, irradiated Hawaiian
PAPAYAS, available in a 1-day trial in Southern California, outsold
the identically priced nonirradiated counterpart by greater than 10 to
1. Irradiated apples marketed in Missouri were also favorably
received. Record amounts of irradiated strawberries were sold in
Florida in 1992 and irradiated strawberries, grapefruit, juice
oranges, and other products continue to outsell their nonirradiated
counterparts in a specialty produce store in Chicago, Ill."

Additional Links

A research service specific to agriculture- these may be able to help-
here are some of their already completed research reports on papayas:

some excerpts:

"Some commodities can be damaged at radiation doses between 0.25 and
1.0 kilogray," McDonald said. "Generally, nonfruit vegetables like
lettuce are much more sensitive to irradiation stress than fruits like
apples or fruit-vegetables like tomatoes."

"According to Luscher, the Jamaican papaya industry and the Florida
sweetpotato, blueberry, and longan industries have asked CDFA to allow
irradiation to fulfill quarantine requirements for their produce to
enter California."

Heated Air Blasts Papaya Pests
... Commercially grown papayas from Hawaii are so carefully checked
... uses humidity differently.
Another approach, irradiation, requires equipment not yet available ... 

Heated Air Blasts Papaya Pests
... Commercially grown papayas from Hawaii are so carefully checked
... uses humidity differently.
Another approach, irradiation, requires equipment not yet available ... 

ARS Project: Pests and Diseases of Papayas (403227)
... Research > Research Project: Pests and Diseases of
Papayas ... Project Number: 5320-22430 ...

ARS Project: Pests and Diseases of Papayas (403227) Annual ... 
... development of transgenic plants with delayed fruit softening characteristics.
Transgenic papayas were produced with the potential to have delayed ripening ...

World Food Chemical News
August 9, 1995 p.10 (LexisNexis)

"...even Japanese consumer groups have threatened to boycott fruit
from Hawaii if the Hawaiian fruit industry starts using irradiation on
a regular basis.  On July 25, the groups released a collective letter
of protest against two recent shipments of Hawaiian fruit treated with
irradiation at an Isomedix irradiation facility in Morton Grove, Ill.,
and test-marketed in U.S. stores."

Do to time constraints, I wasn't able to acquire any information from
Isomedix, but you may be able to contact them and receive some
information (there is a contact link on the upper right side of the

Keeping Food Germ-Free
Mechanical Engineering

1997 Environment Hawai`i, Inc. 
Volume 7 Number 10 (April 1997) 
Little-Known Panel Gets Funds From State To Promote Irradiation
ARS Subtropical Horticulture Research Station

Some Pros and Cons of Food Irradiation
1997 Environment Hawai`i, Inc. 
Volume 7 Number 8 (February 1997)

Council for Agricultural Science and Technology, Radiation
Pasteurization of Food, CAST Issue Pap. 7, 1996

J. F. Diehl, Safety of Irradiated Foods, 2d ed., Marcel Dekker, 1994 

J. F. Diehl and E. S. Josephson, Assessment of wholesomeness of
irradiated food (a review), Acta Alimentaria, 23(2):195-214, 1994

International Atomic Energy Agency, Food Irrad. Newsl., 20(2), Suppl.
A and B: Clearance of Item by Country, and Clearance of Item by Name,

Marguerite Beyers, Austin C. Thomas, and Adrian Van Tonder. 1979. (-
Irradiation of Subtropical Fruits. 1. Compositional Tables of Mango,
Papaya, Strawberry, and Litchi Fruits at the Edible-Ripe Stage. J.
Agric. Food Chem., 27(1): 37-42.

I realize the following sources are old- but it seems that much
research was done on irradiation around this time:

Moutschen, J et al. 1965. Cytological effects of irradiated glucose.
Radiation Botany 5: 23-28.

Chopra, V.L. et al. 1963. Cytological effects etc. Radiation Botany 3: 1-6.

Chopra, V.L. et al. 1969. Lethal and mutagenic effects etc. Mutation
Research 8: 25-33.

Aiyar, A.S. et al. 1977. Studies on mutagenicity etc. Mutation Research 48: 17-28.

Berry, R.J. et al. 1965. Cytotoxic agent in gamma-irradiated carbohyd.
solutions. Int. J. Rad. Biol. 9(6): 559-572

Kesevan, P.C. et al. 1966. Cytotoxic etc. human leukocytes. Current
Science 35: 403-404.

Shaw, M.W. et al. 1966. Effects irradiated sucrose on human
lymphocytes. Nature 211: 1254-1256.

Schubert, J. 1969. Mutagenicity and cytotoxicity of irrad. foods etc.
Bulletin World Health Org. 41:873-904

Kesevan, P.C. et al. 1971. Cytotoxic and mutagenic effects etc.
Radiation Botany 11: 253-281

Blood et al. 1966. Feeding of irradiated peaches etc. Toxicol. Appl.
Pharmacol. 8: 247-249

Fowler, E.E. 1971. PL 422/1 - p.4 in: Disinfestation of fruit by
irradiation. Proceedings of a panel on the use of irradiation to solve
quarantine problems in the international fruit trade , organized by
the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture
and held in Honolulu, Hawaii, US of America, 7-11 Dec. 1970. Vienna,
IAEA 1971.

Nature 231, June 4 1977, p. 277

Google Search Terms Used:

"irradiation dosage" or "irradiation dose" and papaya
database research

Unfortunately, I believe I have exhausted my resources. I would
imagine you will have to pay substantial money to acquire the specific
dosages from an industry professional, but I hope this helps.

Anthony (adiloren-ga)

Request for Answer Clarification by phytosan-ga on 30 Apr 2004 08:05 PDT
thank you again for what certainly seems a lot of time invested in the
project. Unfortunately the search strategy somewhat missed the point
of the questions. As mentioned before we are well aware of all
regulatory aspects and the maximum doses permitted by the law.
Consumer controversy is also understood as are alternative treatments
like hot air blasting. Our specific questions are with respect to the
effect our specific treatment has on shelf life specificially with
respect to fungus deterioration such as anthracnose. All other answers
and links may coincidentially be interesting but do not contribute to
our specific problem. Please advise if you would like to narrow your
search or have as rate the answer as is.

One helpful source would be associated with the "Hawaiian Pride"
electron beam irradiator treating Papaya for several years now.


Clarification of Answer by adiloren-ga on 27 May 2004 12:55 PDT
I'm sorry that I misinterpreted your question. I was too hung up on
the dosage aspect and neglected the shelf-life concern. Here are some
sources specifically related to shelf-life:

Scientia Agricola
Print ISSN 0103-9016
Gamma radiation in papaya harvested at three stages of maturation

"Papaya is a fragile, perishable fruit, highly accepted worldwide. To
keep the quality of papaya from harvest to the consumers, conservation
techniques are often used; among them is the application of gamma
irradiation. The objective of this work was to evaluate gamma
irradiation in papayas harvested at three degrees of maturation, in
order to increase shelf life. Papayas were harvested in perfect
quality conditions and selected by skin coloration into three distinct
degrees of maturation: maturation 0, or beginning of yellow
coloration; maturation 1, yellow stripes more developed, and
maturation 2, one third yellow. Half of them were irradiated with 0.75
kGy, while the other half became control treatment. They were analyzed
in four periods of conservation, which were 1 DAI (days after
irradiation refrigerated at 11  1C), 14 DAI, 14 DAI + 3 DRT (room
temperature at 24  2C) and 14 DAI + 6 DRT. The papaya maturation
degree at harvest did not influence the radiation effect. Irradiation
maintained firmness of papaya and, therefore, delayed ripening;
modified the green color of papaya to a lighter, more intense tone,
which determined more homogeneity in the development of the skin's
yellow color (greater values of L* and croma). There was no effect of
irradiation in papaya weight loss, occurrence of diseases, croma of
flesh color, pH and total soluble solids contents."

Irradiation Free Food Hawaii



About the spice industry but makes mention of papaya:


Q&A on Irradiation

Maybe these will help.
phytosan-ga rated this answer:2 out of 5 stars
A lot of effort with little attention to the specific question asked.
A shot-gun approach that provided almost no factual help. Unfortunate
because the time that went into the research obviously was

There are no comments at this time.

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