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GULF COAST STATION MIMEO REPORT 58-4

INSECT AND OTHER PESTS OF CHRYSANTHEMUMS (Revised)

E. G. Kelsheimer

Introduction

The chrysanthemum industry in Florida has become one of the major

flower producing groups. Many of the gladiolus growers have a few acres

as an added endeavor. The flowering schedule is from November to June,

although a few grow throughout the year. According to Smith and Brooke

(4), of the 233 acres of chrysanthemums grown in the 1955-56 season, 222

are in pompons and 11 acres in standards. Slightly more than half the

acreage is under shade, the remainder in the open.

The writer was first introduced to outdoor culture of mums in 1945

at Bradenton. From that time on a list of insects has been assembled with

their control measures.

No chrysanthemum grower can hope to grow a crop and escape the at-

tack from insects and mites, hence his rigid control program (1,2,3). Be-

cause of his spray program a good share of the enemies described are never

given a second thought. However, the home owner, who grows a few for his

own enjoyment may during the year have had all of the insect pests herein

described. Mums are subject to heavy damage by a few serious pests but

specific measures, both preventitive and control give satisfactory results.

Sucking Insects

Aphis

Description of destructive stage. -- Actual size 1/16 inch. There may be

many species of aphis that attack mums but we have two that are pests, the

melon aphis, Aphis gossypii (Glover) and the chrysanthemum aphis, Macrosi-

phoniella sanborni (Gill). They are soft bodied plant bugs, pale green to

dark red or nearly black in color. They may be winge~d-or fwingless, gelet-
/ / .: ...
ally the latter. (See Fig. 1). /

Nature of injury. Aphis feeding causes the plants to beoinc weak and pro-

duce small distorted lhavoq (Soc. Fig. 2), They usually ins' e -

GULF COAST STATION MIMEO REPORT 58-4

INSECT AND OTHER PESTS OF CHRYSANTHEMUMS (Revised)

E. G. Kelsheimer

Introduction

The chrysanthemum industry in Florida has become one of the major

flower producing groups. Many of the gladiolus growers have a few acres

as an added endeavor. The flowering schedule is from November to June,

although a few grow throughout the year. According to Smith and Brooke

(4), of the 233 acres of chrysanthemums grown in the 1955-56 season, 222

are in pompons and 11 acres in standards. Slightly more than half the

acreage is under shade, the remainder in the open.

The writer was first introduced to outdoor culture of mums in 1945

at Bradenton. From that time on a list of insects has been assembled with

their control measures.

No chrysanthemum grower can hope to grow a crop and escape the at-

tack from insects and mites, hence his rigid control program (1,2,3). Be-

cause of his spray program a good share of the enemies described are never

given a second thought. However, the home owner, who grows a few for his

own enjoyment may during the year have had all of the insect pests herein

described. Mums are subject to heavy damage by a few serious pests but

specific measures, both preventitive and control give satisfactory results.

Sucking Insects

Aphis

Description of destructive stage. -- Actual size 1/16 inch. There may be

many species of aphis that attack mums but we have two that are pests, the

melon aphis, Aphis gossypii (Glover) and the chrysanthemum aphis, Macrosi-

phoniella sanborni (Gill). They are soft bodied plant bugs, pale green to

dark red or nearly black in color. They may be winge~d-or fwingless, gelet-
/ / .: ...
ally the latter. (See Fig. 1). /

Nature of injury. Aphis feeding causes the plants to beoinc weak and pro-

duce small distorted lhavoq (Soc. Fig. 2), They usually ins' e -

-2-

growth, causing the tip to be deformed. The leaves curl inward, and when the

flower terminal is infested, the blooms will be deformed. They will infest

open flowers.

Control. Spray with parathion mixed at the rate of 1 pound of 15W to 100

gallons of water. Apply enough of the spray to thoroughly cover the leaves

with a fine mist. The size of plants and size of beds determine the amount

of spray necessary. Do not spray if showing color.

If demeton is used, mix at the rate of 1 1/2 pints of 2 pound active

material per gallon to 100 gallons of water and apply at the rate of 100 gal-

lons per acre as a spray. Applied as a sprinkling, this is 1 gallon of mixed

solution to 435 square feet. If used as a soil application, more water is

required and the solution may be weaker. Use at the rate of 1 pint to 200

gallons of water.

Thrips

Description of the destructive stage. -- Actual size 1/32 to 1/16 inch long.

There are many species that may attack mums, but the records show the chrysan-

themum thrips, Thrips nigropilosus Uzel, Florida flower thrips, Frankliniella

bispinosa (Morg.), the composite thrips, Microcephalothrips abdominalis

(Crawf.), tobacco thrips, Frankliniella fusca (Hinds) and Gowdeys thrips,

Haplothrips gowdeyi (Frankling) to be the most commonly found infesting mums.

The young vary in color from light to dark yellow with some greenish cast.

The adults vary from light brown to brownish yellow. No specific study has

been made of the species.

Nature of Injury. Infest foliage and open flowers. The insects cause gener-

al browning of blooms, especially in warm weather. (See Fig. 3).

Control. The grower has the choice of using dieldrin 50 percent WP at 1/2

poundto 100 gallons throughout the season or of using parathion 1 pound of

15 percent WP to 100 gallons of water up to the time of coloring. At first

sign of coloring use dieldrin at recommended rate. Records so far show no

petal burn when dieldrin is used properly. More recent tests have proven

dieldrin to be superior.

Mealy bugs

Description of destructive stage. -- Actual size 3/8 inch. They are soft

bodied sluggish insects. One species is the citrus mealy bug, Pseudococus

citri (Risso). They are pure white and have a wax coating over them. They

are generally found in clusters on the underneath side of the leaves or in

the leaf axils.

Nature of Injury. Injury is caused to the stems and leaves resulting in a

discoloring and deforming of the foliage.

Control. Spray with parathion 1 pound of 15 percent WP to 100 gallons of

water. The waxy covering on the insects may make penetration of insecticide

difficult so it may be necessary to add a wetting agent or some good deter-

gent.

Tarnished Plant Bug

Description of destructive stage. -- Actual size 1/4 inch long. The tar-

nished plant bug adult, Lygus lineolaris (P. de B) is of a general brown

color with a mottling of white, yellow, reddish brown and black.

Nature of Injury. Small grayish dead areas are left where the insects

have fed. The sucking beak pierces the tissue of the plant, often causing

deforming of the growth and bending of the tip. The wilting of the tips is

a fairly sure indication of the presence of this pest. Almost invariably

the shoots which have been stung produce no flowers. A flower bud pierced

by a tarnished plant bug will not open.

Control. A thorough coverage with a spray of 2 pounds of 50 percent WP DDT

to 100 gallons of water is an effective control.

Southern Green Stink Bug (Pumpkin Bug)

Description of destructive stage. -- Actual size 1/2 inch long and almost

as broad. The full grown southern green stink bug, Nesara viridula (L.), is

of a light green color. The immature stages are bluish, with some red mark-

ings.

-4-

Nature of Injury. Both adult and immature stages damage the foliage and

stems by sucking the juice. Injured plants may turn brown and wither.

Control. Spray with parathion 15 percent WP at 1 pound to 100 gallons of

water or chlordane 40 percent WP 2 1/2 pounds to 100 gallons of water.

Spittle Bugs

Description of destructive stage. -- Actual size 1/8 inch long. The unde-

termined species belong to the Cercopidae. Bits of saliva-like material

adhering to the stems of mum plants denote the presence of the greenish or

yellowish insects. This is the immature form of the spittle bug. (See

Fig.4).

Nature of Injury. The tips of the leaves usually curl where these saliva

masses are present.

Control. DDT applied at the rate of 1.5 pounds active ingredient per acre

which is 3 pounds of 50 percent wettable, has given good economic control.

Lindane at the rate of 1 pint of 25 percent emulsion per acre gives even

better control. The wettable powder is applied at the rate of 0.2 pound

gamma isomer per acre. Toxaphene at the rate of 1 quart of 60 percent emul-

sifiable concentrate (1.5 pound active) per acre has proven equally as ef-

fective. The 40 percent wettable powder is applied at the rate of 1.5

pounds per acre.

White flies

Description of destructive stage. -- Actual size 1/6 inch. There are sever-

al species of white flies (Aleyrodidae) that infest citrus and some of these

may infest pompons. The larvae of these flies are small, light green scale-

like organisms that feed on leaves. They are sucking insects. The adults

are winged and white in color.

Nature of ingry. Plants grown near trees that harbor white flies may become

infested with small white flies that suck the juice of the plant causing it

to turn yellow and die. The larvae exude a honeydew which gives the foliage

a glazed appearance.

-5-

Control. Spray with a parathion 15 percent WP at the rate of 1 pound to

100 gallons of water.

Leafhoppers

Description of destructive stage. -- Actual size 1/20 to 1/4 inch rarely

larger than 1/4. These small yellowish-green insects are particularly trou-

blesome because they are attracted to lights which are an essential part of

chrysanthemum growing. There are no records of the species involved.

Nature of Injury. The insects produce damage to the leaf by sucking out the

juice from the underneath of the leaf, leaving a tiny yellow spot on the up-

per surface. Leafhoppers besides producing damage to the leaves, may carry

virus disease from plant to plant. Spray thoroughly with DDT at recommended

strengths several times during the season. Keep premises free from weeds

and grass or else keep them sprayed with DDT regularly.

Leafhoppers are worse from the latter part of May until the middle of

July. They come in from surrounding vegetation and damage is always greater

on the outside rows and gradually works in toward the center of the planting.

Maintain a clean barren strip around the shade houses.

Mites

Of the plant feeding mites, the Tetranychidae are the most widespread

and the most important economically. There is hardly a plant that is free

of at least one species and all species appear to be pests. Mites are dis-

tributed by wind and by man, being carried on clothing from one part of the

shade to another. Varieties differ in their susceptibility. Iceberg, blue

chip and portrait are quite susceptible to mite attack. Since there are so

many varieties grown at different seasons it is difficult to establish a def-

inite resistance/and or tolerance for these varieties.

The northern or green two-spotted mite, Tetranychus telarius (L) and

the southern or carmine two-spotted mite T. cinnabarinus Boisduval are two

common species. These mites are found on many weeds, so infestation is simple.

The host plants for T. cinnabarinus are unknown. The two-spotted mite has

-6-

Sbeen found on nightshade, pokeweed, hairy indigo and many other plants.

(See Fig. 5).

Description of destructive stage. -- They are very small, the actual size

about 1/64 inch. They are generally more greenish or orange than red.

They are usually found on the under surface of the leaf. (See Fig. 6).

Nature of injury. The first sign of injury on the foliage is the pale

green mottling of upper leaf surface. The mites damage the plants by

piercing the leaves with their stylet-like mouthparts and sucking out the

plant juice near the puncture. Mites produce at such rapid rates that the

populations reach fantastic proportions if left uncontrolled. Wilson (5)

reporting on T. telarius says that the average time for completion of a

generation is 15 days with approximately 24 generations per year. T. te-

larius will produce fine webs. Nothing is known of T. cinnabarinus.

Mite damage to the open flower ready for the market resembles a spray in-

jury which in the case of the blue chip or portrait variety is a browning

and withering of the petals (the flowers look old or past their prime).

On iceberg and pristine a heavy mite population causes a browning of the

white petals sometimes compared with thrips damage. Examination of a

flower under a glass will disclose the presence of the mites.

Control. Control measures vary in effectiveness as regards species, loca-

tion, season of year and abundance of the pest. The establishment of an-

other species, T. cinnabarinus has helped to eliminate some of the confu-

sion due to failures of miticides to control all mite infestation. Some

infestations that were almost pure cultures of T. telarius responded very

well to phosphatic miticides. Varying degrees of success depended on

the preponderance of other species. Plantings infested with T. cinnaba-

rinus did not.respond to the phosphatic miticides. Demeton applied at

the rate of 1 1/2 pints per 100 gallons of water (4-6 ozs. active ingre-

dient) was proven successful upon certain occasions. Parathion 15W ap-

plied at 1/2 pounds to 100 gallons of water has been effective under the

same conditions as those listed for demeton. Aramite used at 1 1/4 to 1 1/2

pounds to 100 gallons of water has proven effective but to a much lesser de-

gree at times under the same conditions as demeton and parathion. Kelthane

WP applied at 2 pounds to 100 gallons of water has proven quite effective

against all species of mites so far encountered.

Assuming 15 days for a complete generation, two sprays at weekly in-

tervals with the third (clean up) gave control of the mites. A well estab-

lished and flourishing population is hard to control.

Plant susceptible varieties together because they will require more

careful spraying than less susceptible ones and there will be less spread

of the mites throughout the shade,

Greenhouse Orthezia

Description of destructive stage. -- Actual size hard to describe as the long

white fluted egg sac of the female may reach a length of 3/4 inch in length.

TIe actual insect, the greenhouse orthesaa, Orthezia insignia Douglas is a-

bout 1/8 inch in length.

Nature of Injury. The insects settle on the leaves and stems of the plants

sucking the juice and causing the plant to become yellow, sickly and finally

to die if not treated.

Control. Spray with parathion 1 pound of 15 percent WP to 100 gallons of

water. Add a wetting agent or detergent to facilitate penetration of the

waxy covering.

Chewing Insects

Leaf tier

Description of destructive stage. -- Actual size, 1/2 inch. This undeter-

mined species ties the foliage together with a web; it ruins the foliage ap-

pearance. Its name is derived from its habit of spinning a light web enclos-

ing two or more leaves or tying together the parts of a single leaf. The cat-

erpillar is very active, and when disturbed will wiggle off the leaf, often

backwards, lowering itself on a silk-like strand.

-8-

Nature of injury, When first hatched, the larvae eat out shallow holes on

the under side of the leaves. As they grow, they enlarge these holes but

usually do not cut through to the upper surface. The result is that the

leaf is skeletonized. When the leaves are webbed together over the bud a

misshapen flower can result,

Control. Direct the spray against the underside of the foliage. Use DDT

or parathion or a combination of the two especially if the insect has rolled

or tied the leaves together. Parathion acts as the fumigant causing the in-

sect to crawl out of the webbed leaves.

Leaf miners

Description of destructive stage. -- Actual size 3/16-1/4 inch long. The

adult is a tiny shining black fly marked with yellow in various ways. Lar-

vae of the serpentine leaf miner, Liriomyza pusilla (Meig.) are yellow or

orange colored and do th? funneling.

Nature of injury. Most common injury is the serpentine mines made by the

small bright yellow to orange larvae. The tunnel leaves the upper and lower

leaf surface intact. Another type of leaf miner is made by an undetermined

species. (See Fig. 7).

Control. Spray with parathion 15 percent WP at the rate of 1 pound to 100

gallons of water.

Corn Earworm

Description of destructive stage. -- Actual size of larvae 1 1/2 to 2 in-

ches. The full grown larvae of the corn earworm, Heliothis zea (Boddie)

are of variable colors ranging from pink, green or yellow to almost black.

There is a dark stripe along the middle of the back divided longitudinally

by a narrow white line.

Nature of injury. They chew the flower buds and also enter and chew the

petals from an opened flower.

Control. Spray with 2 pounds 50 percent DDT to 100 gallons of water plus

1 pound of 15W parathion before buds show color. After buds show color use

-?-

dieldrin at 1/2 pounds per 100. Dieldrin can be used at 1 pound per 100

without injury to bud or petals.

Cutworms and Armyworms

Description of destructive stage. -- Actual size 1 1/2 to 2 inches. These

are of various colors and markings. There are several species.

Nature of injury. Cutworms cut off the young plant and armyworms eat the

foliage and chew buds. (See Fig. 8).

Control. Chlordane applied to the soil at the rate of 2 1/2 pounds of 40

percent wettable to 100 gallons of water or a 5 percent dust will control

the larvae. Heptachlor applied at the rate of 2-3 pounds of 25W per 100

gallons or dieldrin applied at the rate of 1 pbund do the 50W are also ex-

cellent controls. In commercial plantings, soil sterilization keeps these

pests under control.

Sowbugs

Description of descructive stage, Actual sise 3/8 to 5/8 inch. They

are dark gray ith a lighter gray underneath. Trey are crustaceans, rela-

ted to crayfish and crabbi ad dia not inisets. They are found in moist

areas usually ieal eboe decayed matter. They siddbm appear during the

daytime

Nature of injury. They feed on the roots and tender portions of the plant

Control. Chlordane applied to the soil as a spray at the rate of 2.5 pounds

of 40 percent WP to 100 gallons of water or 30 pounds of 5 percent dust or

granules will control these pests.

Salt-marsh caterpillar, Woolly bear

Description of destructive stage. -- Actual size of full grown larvae of

the woolly bear, Estigmene acraea (Drury) is 2 inches in length. The lar-

vae are hairy or woolly brown to dark brown in color.

Nature of injury. The pest may move in rapidly from adjoining fields and

overnight ruin blocks of chrysanthemums. Because the pest is migratory and

capable of fast locomotion, it can damage considerable areas in a short time.

-10-

Migrating larvae are heavy feeders and are difficult to control.

Control. This pest is the one exception where a dust is advis"aledespite

the stage of growth of the mums because of the voraciousness of the insect.

A thorough dusting of 10 percent DDT will control the pest. It is necessary

to repeat the dusting within a day or so to kill caterpillars missed by the

first dusting.

Grasshoppers

Description of destructive stage, -- Various sizes up to the large lubberly.

There are several species.

Nature of injury. Grasshoppers can move in suddenly and cause severe damage

to flowering plants by eating foliage, flowers and tender growth.

Control. Aldrin applied at the rate of 1/2 pint of the emulsifiable concen-

trate per acre is effective. Toxaphene sprayed at rate of 1.5 io 2 pounds

of the 40 percent wettable per acre is effective.

Geometrid measuring worms

Description of destructive stage. -- The larvae of this group are called

measuring worms, spanworms or loopers because of their method of locomotion,

which is one of looping or measuring. Identification is made easier because

these larvae do not have any legs in the middle of the body, only at the

head end and rear end. They can attach themselves by their rear legs and

assume the likeness to a dry twig. One species known to attack mums is

Synchlora rubrifrontaria Pack.

Nature of injury. Injury results from their eating leaves or florets.

Control. Apply DDT 50 percent WP at rate of 2 pounds to 100 gallons of water.

Cabbage looper

Description of destructive stage. -- Actual size of full grown larva is

1 1/4 inches. The pale green larvae have a narrow white stripe along each

side of the body and two others along the middle line of the back. They

travel with a looping measuring motion of the body.

Nature of injury. The young larvae eat small holes in the leaf but do not

-11-

-completely penetrate the leaf. As the larvae increase in size they eat the

more tender leaves and frequently ruin the bud.

Control. DDT applied at the rate of 3 pounds of 50 percent WP to 100 gal-

lons of water or toxaphene at 1 1/2 pounds of 40 percent WP will control the

insect. Do not dust because of danger of spotting the petals.

Termites "white ants"

Description of destructive stage, -- Actual size variable about 3/16-3/4

inches. The destructive stage are wingless, usually pale-colored, soft bod-

ied and possess chewing mouthparts. They are called white ants but are not

an ant or related to ants.

Nature of injury. Termites have caused the loss of many chrysanthemum

plants around the home. They injure or kill a plant by tunnelling the stem.

Around the home, a wilted plant is a likely suspect for termite injury. Cut-

ting across the stem will frequently reveal the presence of the termites.

Nothing can be done for the plant once the termite attack has progressed

this far.

Control. Termites can be eliminated from the soil by the use of chlordane,

dieldrin or certain gaseous soil fumigants, such as MC-2, DD or EDB. The

chlordane or dieldrin is applied to the soil at the rate of 1 ounce of ac-

tive material to 1000 square feet.

General Recommendations

All dosages, if a spray, are given for a certain poundage of the in-

secticide per 100 gallons of water. Normally, an acre of pompons requires

2400 gallons of spray. There are certain right and wrong methods of appli-

cation depending upon the type of pest to be controlled. For most purposes

a spray directed upward through the foliage is much more effective because

very few if any growers will apply an insecticide alone; they are generally

in conjunction with a fungicide and a nutrient. A three nozzled spray jet

is the most satisfactory. It is very important that the nozzles be the same

type and the size of the orifices the same or uneven spraying will result

-12-

causing irregular control patterns.

References

1. Ball, George J., Inc. Ball Mum Guide. 1955.

2. Gloeckner, Fred C. & Co., Gloeckner's Chrysanthemum Manual. 1952.

3. Kiplinger, D. C. Greenhouse and Garden Chrysanthemum. 1954.

4. Smith, Cecil N. and Brooke, Donald L. Tje Florida Chrysanthemum Industry.
Agr. Ec. Mimeo Report 56-10. Fla. Agr. Expt. Sta. 1956.

5. Wilson, J. W. The two-spotted mite on asparagus plumosus. Fla. Agr.
Exp. Sta. Bul. 234, 1931.

350 copies
Sept, 27, 1957