Disease symptoms
 Carried on corms
 Control measures

Group Title: Mimeo report - Gulf Coast Station - 54-8
Title: Gladiolus Stromatinia disease
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067635/00001
 Material Information
Title: Gladiolus Stromatinia disease
Series Title: Gulf Coast Station mimeo report
Physical Description: 5 leaves : ; 28 cm.
Language: English
Creator: Magie, R. O ( Robert Ogden ), 1906-
Gulf Coast Experiment Station (Bradenton, Fla.)
Publisher: Gulf Coast Station
Place of Publication: Bradenton Fla
Publication Date: 1954
Subject: Gladiolus -- Diseases and pests -- Florida   ( lcsh )
Gladiolus -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: R.O. Magie.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067635
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 71356041

Table of Contents
    Disease symptoms
        Page 1
    Carried on corms
        Page 2
    Control measures
        Page 3
        Page 4
        Page 5
Full Text


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida



R. 0. Magie

The gladiolus disease commonly called dry rot in other areas has been called

Sclerotinia neck rot in Florida because dry rotting of corms is not known to occur

in peninsular Florida. The fungus which causes this neck rot and dry rot was re-

cently found to belong to a closely related genus and is now named Stromatinia

gladioli (Drayton) Whet. This fungus was not known to cause a serious disease of

the roots until 1953-54 when losses were heavy in some Gulf Coast farms. The loss

in the Tampa Bay area alone is estimated to be over'$100,000.

Dry rot of corms and neck rot caused by Stromatinia is a major disease of

gladiolus in Western Washington, parts of Michigan and some other regions where

growing-season temperatures are relatively low and rainfall is plentiful. In Florida

the neck rot has been most severe when unusually cool weather occurs in October or

the first two weeks in November,

Moisture is an important factor in disease development. Root infection was

most severe in the lower and wetter parts of fields. Neck rot has been most prev-

alent in seasons of abundant rainfall. poot rot was found to be severe in some

fields where neck rot was scarce or absent.


Stromatinia neck rot may appear similar to Fusarium yellows and the root rot

looks like other root rot troubles. However, the disease may be positively identi-

fied by the small, round, black sclerotia which are imbedded in the dead tissues.

These sclerotia can lie dormant in the soil for one or more years. Some of them

stay alive for many years. A magnifying glass should be used to find these shiny,

black, pimple-like bodies on the roots.

It is often difficult to find gclerotia on the roots because sclerotia are not

formed until the tissue has been dead for several days or weeks and because the outer

part of the root usually sloughs off, leaving the sclerotia in the soil. Sclerotia

are found only in the cortex or bark of the root, They are seen more readily when

the roots are washed and dried.


Infected roots turn yellow and brown. After the softer, outer part sloughs

off, the central, woody part of the root is often found to be white and tough with

a wiry, rough texture when dry.

In the neck rot phase of the disease the outer leaves are killed first. The

sclerotia usually are not formed until the whole neck is rotted. The rotted neck

tissues become very dark brown and shredded. The dead stalk may be pulled away

from the corm easily. In contrast to plants killed by Fusarium, the corm is found

to be sound but stunted.

Corms are usually attacked by way of the husks or leaf bases. Shallow black

lesions develop along the lines of husk attachment. Occasionally the disease fol-

lows the vascular tubes into the core. The infected vascular tissue is greenish

black or dark brown.


Corms which appear to be free of any infections may carry the fungus to the

soil. The fungus spreads from corm to corm and root to root. If the weather is

relatively dry and warm, there is little or no above-ground evidence of disease

but enough sclerotia may be produced on roots to initiate serious disease develop-

ment in future plantings on the infested land. Severe loss from Stromatinia was

experienced in a field planted with seedling corms. The infection came from the

soil, not from the corms, because they were grown from seed in a seedbed of methyl

bromide-treated soil. This field had been planted to gladiolus only once before

with untreated corms from an out-of-state source. Enough sclerotia to initiate

this severe epidemic were produced, probably on the roots, without any obvious, a-

bove-ground disease symptoms in the January planting of corms that preceded the epi-


The disease originates both from corms that carry the fungus and from sclero-

tia in the soil. When it originated from corms, neck rot appeared as early as Octo-

ber 1 in a September 8 planting on new land. When the disease originated only from

sclerotia carried in the soil, however, neck rot did not develop until November or

December, indicating that periods of cool weather are required to activate the dor-

mant sclerotia.



Rotation of fields. -- In gladiolus areas on the Gulf Coast, new fields

should not be planted in consecutive years unless the corms are grown from corm-

lets and planting stocks produced on clean land. Fields which showed neck rot

or root rot should not be planted to gladiolus for at least two years. During

the years when gladiolus are not grown in a field, care must be taken to keep down

the growth of volunteer gladiolus by disking, at least during October, November,

December and January when sclerotia would be produced abundantly. This also ap"-

plies to fields in which late winter plantings are to be made. The infection could

spread from the volunteers to the new planting, even though the volunteers were

plowed under.

Time of planting. -- As mentioned above when clean corms were planted in

contaminated or diseased soil, neck rot symptoms did not appear in plantings made

before September 15 or after January 15. Cool temperatures which normally occur

in November apparently are required to activate many of the sclerotia remaining in

the soil. Field evidence also indicates that those sclerotia which are susceptible

to stimulation by cool weather have mostly germinated before January and are no

longer able to attack gladiolus. November and December plantings were most severe-

ly attacked, presumably because the plants became diseased during the early stages

of growth. When plants were not attacked until they were mature, disease development

was sparse but sclerotia were produced in numbers sufficient to initiate severe epi-

demics in future years.

Sanitation. -- Whenever possible, clean land should not be contaminated by

planting diseased corms, or corms that grew on contaminated land, if gladiolus are

to be grown in those fields in subsequent years. Such corms may be planted on con-

taminated or questionable land in August or after January 15 because the disease is

less severe in very early or in very late plantings.

Contamination of soil by sclerotia may be reduced somewhat by pulling out

plants at the first sign of neck rot, by harvesting early and by raking the tops

off the field immediately after corm harvest.


Drier soil, high beds and lower water table would probably help in control-

ling the disease because the fungus is reported to grow through wet soil more rapid-

ly than through drier soil. Corms planted during October through December may be

covered with as little as an inch of soil until the third week. This would reduce

neck rot infection. The planting furrows should be filled and the beds built up

gradually over a period of four weeks.

Corm treatment is very helpful in controlling Stromatinia disease, especially

when plantings are made in uncontaminated or relatively "clean" soil. Corm treat-

ment will not prevent all disease development and sclerotia formation. Dr. C. J.

Gould in western Washington found that the N. I. Ceresan dip is one of the most ef-

fective preplanting treatments. However, because Ceresan reduces flower yield in

that area, he recommends Tersan for treating corms in dry rot control.

Corms of all varieties and of all sizes should be treated. Since control of

Fusarium disease is of prime importance in Florida, the following treatments are

suggested for both diseases.

A. For Picardy corms and other varieties that are fairly tolerant of N. I. Ceresan


1. After cleaning corms wait 4 to 18 hours and then soak them 15 minutes in solu-

tion of 2 pounds Dowicide B in 50 gallons water plus 1/2 cup of detergent such

as Glim or Joy. Before planting these corms, soak them for one minute in 1

pound of N. I. Ceresan wetted with detergent and mixed in 50 gallons of water.

The one-minute treatment has resulted in better flower production and nearly

as good disease control as the ten-minute treatment.


2. Soak conms for 10 minutes just before planting in 1 pound N. I. Ceresan wetted

with detergent and mixed in 50 gallons of water.

B. For Valeria corms and possibly other varieties that are injured by the regular 10

or 15-minute N. I. Ceresan treatment.

1. Same as No. 1 above



2. Soak corms 15 minutes in mixture of 5 pounds thiram 75 percent wettable (Tersan

75) in 50 gallons water. Stir before' each batch of corms and agitate corms in

the dip. This chemical is expensive but the dip can be re-used indefinitely if

more of the fresh dip is added to maintain volume.

C. No treatment is recommended for cormlets. Tests are being made to find an effec-

tive but safe treatment.

Soil treatment, using 1500 lb. calcium cyanamid per acre, was fairly effec-

tive in one test. A period of at least 60 days must elapse between the broadcast

application and the planting of gladiolus. Wait another month if the soil is not

continuously moist following treatment. A waiting period of 90 days is suggested

for winter and spring applications because gladiolus are very sensitive to the break-

down products of cyanamid.

Flooding may prove to be very helpful in controlling the gladiolus Stroma-

tinia disease because it is effective against sclerotia of similar fungi. Flooding

of soil for three weeks during summer or early fall is effective in killing the glad-

iolus Fusarium. If the water can be held high e;icuh to cover the surface for at

least three weeks, gladiolus fields which have been cropped several times would be

greatly benefited.

This disease is much more damaging and widespread than previously recognized

and will probably tend to become more severe as fields and corm stocks become more

generally infested. It appears that some cases of gladiolus root rot which were

blamed on nematodes were probably caused by Stromatinia. The fact that the fungus

becomes established in the soil so quickly and spreads from plant to plant so read-

ily makes this a major disease. The most important considerations in avoiding heavy

losses from Stromatinia are 1) Rotate fields, planting gladiolus once in three years;

2) Avoid planting corms from "diseased" land in "new" land; 3) Plant infested corms

or infested fields very early or very late in planting season; 4) Treat corms and 5)

Use the minimum irrigation riter necessary to produce quality spikes.


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