U. S. Forest Seruice Research Note SE- 7 July 1963 PINE TIP MOTH DAMAGE TO PLANTED PINES IN SOUTH FLORIDA Resistance to insect attack is an important consideration to the landowner or manager who must decide which tree species to plant. Results from several studies in artificial regeneration of pines in south Florida indicate that the in­ digenous slash pine variety, South Florida slash pine (Pinus elliottii var. densa Little & Dorman), is less susceptible to a pine tip moth(Rhyacionia subtropica Miller) than other commonly planted southern pines. Early planting studies on the Corkscrew Experimental Forestlf in south Florida included both typical slash pine (Pinus elliottii var. elliottii) and the South Florida variety. The incidence of pine tip moths in the terminal leaders was inventoried in plantations established in 1952, 1953, and 1954. The num­ ber of trees inventoried varied from 106 typical slash pine in the 1952 planting to 8,814 South Florida slash in the 1954 planting. Data from the early plantations showed that typical slash pine were not only more susceptible than South Florida slash pine to leader infestation by pine tip moths (table 1), but that injury to typical slash was severe, often resulting in death of the infested leader, deformation, and sometimes death of the tree. Although some damage was recorded every year, widespread attacks began the fourth year after planting, the most serious damage 5 years after planting. Table 1. --Incidence of pine tip moth infestation in Additional data on pine tip the terminal leaders of slash pines at age 5 on moth attacks were obtained from the Corkscrew Experimental Forest a study installed in 1955 to test four pine species at eight locations Planting date South Florida Typical slash (year) slash throughout south Florida (fig. 1). Species included typical slash, - - - Percent - - - South Florida slash, loblolly (Pinus 1952 75 6 taeda L.), and longleaf pine (Pinus palustris Mill.). Careful records of 1953 79 5 insect infestation were maintained. 1954 70 8 1/ A 4,000-acre tract in Collier County, Florida, owned by the Alico Land Development Company and leased for research purposes to the Southeastern Forest Experiment Station in cooperation with the Florida Board of Forestry. I >.. \-..... \).. ~,..,1 ... ,--1~( - - ----l.... 7Tt-.1~ rJ - ..... 7-_ •. 5j1I .-+-=:_? - .... \ '1 -5 I "'- t-.=- .: ---t-· - --- -- - I 'f- rffil Cork~ew'---1 '-·-7 -- 8 - L.__ __. - I Figure 1. --Location of the eight species comparison plantings in south Florida. A pine tip moth, Rhyacionia subtropica Miller; a pine sawfly, Neodiprion merkeli; the pine webworm, Tetralopha robustella; and Dioryctria amatella were noted in some or all of the plantings established in 1955. 2/ However, only pine tip moth damaged trees appreciably (table 2). Data from this study not only confirmed observations from the earlier plantations that typical slash pine is more susceptible than South Florida slash pine to attacks from pine tip moth, but also indicated that the relative susceptibility of typical slash varied considerably by location. Incidence in typical slash pine increased from north to south for the four southwest Florida plots, but the pattern. did not hold true for the southeast Florida plantings. There, the incidence of pine tip moth dropped from location 6 south. 5!/ Specimens were identified by E. P. Merkel and B. H. Ebel, Entomologists, Olustee Research Center, Olustee, Florida. I Table 2. --Incidence of pine tip moth infestation in the terminal leaders of 6-year-old pines planted at eight south Florida locations in 1954-5511 Infestation on-- Location Vegetative cover (number) T . al h [ South Florida I yp1c s 1as slash Loblolly I Longleaf - - - - - - - - - - - Percent - - - - - - - - - - - 1 Cutover longleaf 8.4 2.7 2.2 0.9 2 Cutover longleaf 18.3 2.4 8.0 1.2 3 Cutover South Florida slash 27.8 6.6 15.3 .8 4 Cutover South Florida slash 52.0 6.8 14.4 .o 5 Cutover longleaf 13.8 4.2 20.9 .6 6 Cutover South Florida slash 47.6 9.4 10.4 .o 7 Cutover South Florida slash 28.1 14.8 15.2 .o 8 Drained saw grass marsh 10.1 9.5 13.6 .o All sites 25.8 7.0 12.5 .4 11 196 trees of each species were planted at each location. Pine tip moth infested a larger percentage of typical slash pine than South Florida slash pine at every location, More typical slash than loblolly were infested at six of the eight locations; and more loblolly than South Florida slash pine at seven of the eight locations, Pine tip moth attack on longleaf pine was negligible. Rhyacionia subtropica Miller has been identified on both varieties of slash pine, on longleaf pine, loblolly pine, and tropical pine (Pinus tropicalis). ~ However, typical slash pine has been considered quite resistant to pine tip moth within its natural range, 1/ and until recently, longleaf has been regarc:led as immune to its infestation. W The increased susceptibility of these species in south Florida may be because typical slash pine does not extend naturally into ~ Miller• William E. A new pine tip moth (Olethreutidae) from the Gulf of Mexico region. Jour. Lepidopterists' Society 14: 231-236. 1960. 1;/ Yates, Harry O. III. Influence of tip moth larvae on oleoresin crystallization of southern pines. U. S. Forest Serv. Southeast. Forest Expt. Sta. Res. Notes 174. 1962. fl/ Yates, Harry 0, III. The Nantucket pine moth. A literature review. U, S. Forest Serv. Southeast. Forest Expt. Sta. Paper 115, 19 pp •• illus. 1960, li the area studied, and longleaf pine is near or below its southern limits at these locations. Species planted at or below their limits of natural distribution are reported more than normally susceptible to injury from pine tip moths. 9/ In south Florida. plantings of typical slash can be expected to experience severe tip moth damage. 9/ Wakeley, Philip C. Planting the southern pines. U. S. Dept. Agr. Monog. 18, 233 pp., illus. 1954. James E. Bethune Agricullure - Arbevill• Fort Myers, Florida .