Pest 411 Tea scale

Tea scale

A major pest on hollies and camellias

by Gurjit Singh and Shimat V. Joseph, UGA Department of Entomology

Lorraine Graney, Bartlett Tree Experts, Bugwood.org Fig. 1. Brown-colored females (red arrow) and white-colored males (orange arrow) of tea scale.

Chazz Hesselein, Alabama Cooperative Extension System, Bugwood.org Fig. 2. Yellow spots on upper side of camellia leaves due to tea scale feeding underneath. Tea scale, Fiorinia theae (Hemiptera: Diaspididae) (Fig. 1) is a serious economic pest of camellias and hollies in nursery and landscape. Tea scale is an armored scale that causes chlorosis of the leaf tissues and under severe infestations, plants may die.

The insects undergo multiple overlapping generations in a year and are very challenging to control. Even after the control measures are administered, the plant retains the damaged leaves for at least a season. It usually takes 2-3 years to bring the infestations under control after application of effective insecticides.

It is an invasive pest native to Asia and thought to be introduced into the US in early 1900s. Currently, it infests numerous plant species throughout the warmer regions of the world. In the US, its range varies from Florida, Georgia, South Carolina, and Louisiana in the southeast to Texas and California in the west. It mainly causes economic losses to camellias and hollies. In India, where it was first described, it has been reported on tea (Camellia sinensis), olives (Olea europaea), and citrus (Citrus sp.).

Identification and biology

Growth and developmental rate of tea scale varies with the region's environmental conditions. This pest completes a life cycle in 45-65 days depending upon the temperature. In Florida, it is active throughout the year, but in the colder regions of Georgia and South Carolina fewer yearly generations are observed.

An adult female tea scale lays two rows of 10-15 eggs under the scale covering, which hatch within two weeks. Tea scale undergoes three nymphal stages. The newly hatched scale nymphs, called crawlers, move from one plant to another by wind and crawling and spread the infestation. Within a week, these crawlers insert their piercing and sucking mouthparts into the succulent plant tissues underneath the leaf and become immobile. After 10 days, the crawlers molt into second nymphal stage. Thereafter, they lose all the appendages (legs and antennae) and remain immobile. Females (Fig. 1 [red arrows]) retain the skin from the first molt which becomes sclerotized over time and give the adult female its characteristic brown color. The adult females are 1/10th of an inch in length. The nymphal stages of males are initially yellow but as they grow, they secrete a thin soft white waxy shield (Fig. 1 [orange arrows]). Adult males develop a pair of wings, a pair of halteres and non-functional mouthparts. The adult males are usually smaller than the females.

Symptoms and damage

The tea scales pierce the plant tissues underneath the leaves and suck the sap causing chlorosis or yellowing on the upper leaf surface (Fig. 2). Infested plants look unhealthy with fewer and smaller blooms. Under heavy infestations, white cottony filaments can be seen hanging from the leaves and the twigs dieback, sometimes causing death of the plant (Fig. 3). Dead scales and damaged leaves remain on the plant for a season or two, making the plant aesthetically unappealing to consumers.

Monitoring and management

Several parasitic wasps have been found parasitizing tea scale in Georgia and Florida, including Aphytis diaspidis and two species of Aspidiotiphagus spp. Prior to making insecticide applications, efforts should be made to ensure that the scales are not naturally managed by the native parasitic wasps. Parasitized scales have detectable holes chewed out of their armors by the emerging parasitic wasps and are surrounded by the patches of necrotic tissues.

Low to moderate level of infestations can be easily controlled with the horticultural oils. However, in most cases, damage has been done before the scale infestation is actually noticed. Insecticide applications are usually started in the beginning of April to coincide with the emergence of crawlers, when insecticides are most effective. Tea scales are often very difficult to control because they infest the underside of the leaves, because they reproduce continuously in warmer months, and because the waxy armor provides protection. Pruning can be a very effective tool against this pest as it would not only improve insecticide exposure but also improve the air circulation. Furthermore, adding an adjuvant to the spray mixture and directing the spray Shimat Joseph, University of Georgia towards the underside Fig. 3. Heavy tea scale feeding on hollies. of the plant foliage will definitely enhance the effectiveness of chemical control. For lasting results, foliar application using contact insecticides should be repeated 2-3 times at 7-10 day intervals. Among systemic insecticides, dinotefuran is effective but multiple applications are required because the residue activity of dinotefuran does not last long enough to control multiple generations of tea scale. Other neonicotinoid insecticides such as clothianidin or imidacloprid may not be as effective as dinotefuran.

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CONDITIONSOFSALESellerwarrantsthatthisproductconsistsoftheingredientsspecifiedandisreasonablyfitforthepurposestatedonthislabel whenusedinaccordancewithdirectionsundernormalconditionsofuse. Noone,otherthantheofficerorSeller,isauthorizedtomakeanywarranty, guarantee,ordirectionsconcerningthisproduct.Becausethetime,place,rateofapplicationandotherconditionsofusearebeyondSeller’scontrolSeller’s liabilityfromhandling,storageanduseofthisproductislimitedtoreplacementofproductorrefundofpurchaseprice.Buyerassumesallresponsibility forforsafetysafetyandanduseusenotnotininaccordanceaccordancewithwithlabellabelinstructions.instructions.TheproductnamesareregisteredtrademarksofGreeneCountyFertilizerCompany,Inc.

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Compatibility: These concentrated materials are compatible with most fertilizers and chemicals but should not be mixed directly with other chemicals. Conduct a jar test as needed to ensure compatibility before tank mixing. Mix in spray tanks with water and proper agitation.Apply in accordance with best management practices (BMP’s) established by your Cooperative Extension Service. Observe any State or Local fertilizer application regulations. Caution:Caution: This product contains the secondary micronutrient iron. Iron may stain concrete, wood and other pervious and impervious surfaces. Apply only to turf, plants, and soil. If plants are flowering, apply to base of the plant to avoid staining of blooms. Keep out of reach of children. If product comes in contact with skin or eyes flush with water immediately.

Manufactured and Guaranteed by Greene County Fertilizer Company, Inc. ▪ P.O. BOX 1346, Greensboro, GA30642 ▪ 1-855-606-3378 ▪ GreeneCountyFert.com ▪ F2735

1.0 gal=10.7 lbsat 68° F □ net volume2.5 gal (9.5 l) □ net volume5.0 gal (18.9 l) □ net volume275 gal(1041.0 l)

CONDITIONSOFSALESellerwarrantsthatthisproductconsistsoftheingredientsspecifiedandisreasonablyfitforthepurposestatedonthislabel whenusedinaccordancewithdirectionsundernormalconditionsofuse. Noone,otherthantheofficerorSeller,isauthorizedtomakeanywarranty, guarantee,ordirectionsconcerningthisproduct.Becausethetime,place,rateofapplicationandotherconditionsofusearebeyondSeller’scontrolSeller’s liabilityfromhandling,storageanduseofthisproductislimitedtoreplacementofproductorrefundofpurchaseprice.Buyerassumesallresponsibility forforsafetysafetyandanduseusenotnotininaccordanceaccordancewithwithlabellabelinstructions.instructions.TheproductnamesareregisteredtrademarksofGreeneCountyFertilizerCompany,Inc.

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