LEDIN: COLD DAMAGE 341

thousand boxes of Lulas and a smaller quan cultivation of young groves, and keeping all tity of other varieties were salvaged. trees in healthy condition, there are not many This did not apply in equal measure to things to do. In young groves, if the every variety, and it most certainly does not are small enough to be covered by hampers apply to the we harvest earlier in the this should be done. It will prevent injury season. Observations in freezes occurring from mild freezes and will save the life of earlier in other winters show definitelv that the plants at temperatures as low as 27 de while Lula fruit will stand the cold well even grees. Older trees can be protected by firing, early in the season, many varieties cannot be as in citrus groves, but this is not often done salvaged at all if the temperature drops as as the need for it is not frequent and the ex low as 28 degrees. The damage is not always pense is great. The few groves that were pro manifested in the way just described, either. tected by oil heaters last February came Fruit which appears perfectly good on the through with little damage, but where old outside may "cut black" around the . And automobile tires were burned, as is frequently some varieties will drop badly after a cold done for truck crops, I could not see that they spell which did not even damage the . afforded much protection. Whether or not Oddly enough, some of the varieties which oil-firing is economically justified as a general are quite susceptible to cold damage in No practice would require a careful cost study; vember or Decembercame through this cold the answer is not available to us now. as well as the Lula. I have in mind particularly We have no experience with wind machines, the Booth 1, which will rain off the trees after but it seems to me that this device may prove temperatures no lower than 29 or 30 degrees to be a valuable aid in protecting from most early in the season; the fruit of this variety of our freezes. stood the cold in February as well as did the I will concludewith the sober observation Lula. There may be a change in the fruit that except for what we have learned about associated with full maturity which makes it keeping the trees healthy, the value of keeping able to stand more cold. the groves clean, and the possibility of sal Any discussion of cold injury should in vaging fruit from injured trees, we are in clude the subject of protective measures. Ac about the same positionthat we were 25 tually, in Dade County, aside from the clean years ago, when it gets cold.

COLD DAMAGE TO FRUIT TREES AT THE SUB-TROPICAL

EXPERIMENT STATION, HOMESTEAD

R. Bruce Ledin for 13 hours and an official low of 26.5° F. Sub-Tropical Experiment Station was recorded at the Station. Except for one warm week the end of December and a few Homestead warm days during January, cool weather pre The numerous cold spells of the winter of vailed until February 22. 1957-58 provided an opportunity to evaluate In most cases damage by the February 4-5 the hardiness of some tropical and subtropical freeze was more severe than that of January fruit plants. At the Sub-Tropical Experiment 14-15, 1956, when temperatures below 32° Station, Homestead, the December 9-12 cold F.lasted for 8 hours and an official low of spell reached a low of 32° F. but did very 27° F. was recorded. Some plants, however, little damage except to sensitive plants and received more damage in 1956 than in 1958. those still in active growth. During the Janu Susceptibility of plants to cold damage de ary 8-9 cold spell two hours below 32° F. pends on several factors. caused no damage. The February 4-5 cold 1. The nature of the species—some species spell, on the other hand, did considerable are extra tropical, such as the bread damage; temperatures below 32° F. lasted fruit, Malay , and cashew, and will 342 FLORIDA STATE HORTICULTURAL SOCIETY, 1958

sometimes be damaged by cold even with irrigation ditches between. During cold without freezing temperatures. spells water was run into the ditches and al 2. The general condition of the from lowed to flood the beds. Unfortunately we a nutritional standpoint — if chlorotic, do not have any temperature records in the lacking fertilizer, especially nitrogen, or flooded area, but the official temperature on weakened by insects or diseases, the higher ground February 5 was 27.5° F. with plants will be more susceptible to cold 6 hours below 32° F. It was quite evident injury than those in good healthy con that the water kept the temperature above dition. freezing, as very little damage occurred to these plants, except for some that were situ 3. The stage of growth—a tree in active ated at the ends of the beds which were not growth with tender leaves is more sus flooded. One star-apple in this location was ceptible to cold than a tree in dormant injured severely, but star- that were condition. flooded showed little injury. This was also true 4. The age of the tree—a well established of Kent and Zill mangos planted in this same plant 4 years or more of age can tole area. At the Sub-Tropical Station in Home rate more cold than young plants only stead, many of the fruit plants were protected 1 to 3 years in the field. by fire pots and the trunks of young plants 5. Overhead protection — plants growing were wrapped with straw. under large spreading trees or protect In the following lists the plants are grouped ed by nearby trees or buildings will according to the amount of injury. In most not be hurt as much as trees in exposed cases both old and young plants are repre situations. sented; if there was any injury to young plants Cold protection can be provided in several and not to the older ones, this is noted. ways: 1. Species showing little or no damage. 1. Clean cultivation—exposed rock or sand Averrhoa carambola, carambola will permit more accumulation of heat Butia capitata, jelly-palm during the day and allow more radia Carissa grandiflora, Natal-plum. Mature heal tion of heat from the ground during thy plants were uninjured, but a row of the night than ground covered with Gifford carissa that were slightly chlorotic, mulch or weeds. 2. Wrapping the trunks of young plants infested with scale insects, and overgrown with weeds, showed some burn and with straw or some other material that twig injury. is loose enough to allow circulation of air and to prevent accumulation of Casimiroa edulis and C. tetrameria, white-sa- moisture will provide sufficient insu pote. Old plants were unaffected, but 1- lation to protect the trunks even if the year old seedlings at Ft. Lauderdale had a top above the wrap is killed. little leaf-burn and twig injury. 3. Planting sensitive plants where they Ceratonia silique, carob will be protected by large trees. Clausena lansium, wampi 4. Use of fire pots to raise the temperature caffra, kei-apple a few degrees. Dovyalis hebacarpa, Ceylon-gooseberry 5. Covering small plants with hampers or Dovyalis hebacarpa X D. abyssinica, hybrid similar containers. dovyalis 6. Irrigation may be used to raise the air Elaeagnus philippensis, lingaro temperature; overhead irrigation or Eriobotrya japonica, loquat running water into ditches are both Eugenia aggregata, cherry of the Rio Grande effective. Eugenia dombeyi, grumichama Most of the notes on cold damage to the Eugenia luschnathiana, pitomba fruit plants were made at the Experiment Eugenia uniflora, Surinam-cherry Station in Homestead, but some notes were Feijoa sellowiana, feijoa made on plants in our fruit planting at the Macadamia ternifolia, macadamia nut Ft. Lauderdale Field Laboratory. At Ft. Lau- Myrica rubra, strawberry tree derdale the plants are set out on 50 foot beds Prunus persica, red Ceylon peach LEDIN: COLD DAMAGE 343

Psidium cattleianum, strawberry guava Achras zapote, sapodilla. Old trees were un Rhodomyrtus tomentosa, downy myrtle affected and grafted trees 4 years in the Ruhus albescens, Mysore black raspberry field were riot injured. Small plants in ex Triphasia trifoliata, lime- posed situations were killed to the ground Zizyphus mauritiana, Indian Jujube or to the straw wrap. 2. Species showing only slight injury. Artocarpus hypargyrea, kwai muk. Large trees Antidesma dallachyanum, Herbert River-cher had only a little leaf injury; smaller plants ry. This species proved to be hardier than A. showed considerable leaf burn and twig bunius; young plants in exposed places in injury. the same vicinity showed very little dam Artocarpus integrifolia, jackfruit. Very large age. Young plants at Ft. Lauderdale had trees were not hurt except for some exposed more leaf and twig damage. branches on one side of tree were killed; Diospyros discolor, mabolo. Old plants were one and two year old seedlings were killed. unaffected, but young plants had leaf burn Blighia sapida, akee. Large trees had some and some twig injury. leaf burn and twig injury but this was not Eugenia pimenta, all spice. Old plants were as severe as the cold damage in 1956. not damaged but young plants were in Carissa carandas, karanda. Both old and young jured. plants in exposed situations had consider Litchi chinensis, lychee. Old plants in dormant able leaf and twig injury. condition were not damaged; new vegeta Diospyros ebenaster, black sapote. Both large tive flushes and shoots were killed. and small plants were injured, especially Young plants 1 to 2 years in the fields were branches that were exposed. killed back to the straw wrap and a few Euphoria longana, longan. Old trees were not of the weaker plants were killed completely. affected, but a number of 3-year old seed Malpighia glabra, Barbados cherry. Large lings in a windbreak were injured, some plants of the Florida Sweet and other clones killed to the ground, others showed injury which had been fertilized in October were only on the terminal branches. in perfect condition all during the winter. Garcinia livingstonei, imbe. Old plants which A few clones and a number of seedlings, were protected by nearby large trees were especially those which had received no unaffected; plants in exposed situations had October fertilizing, had some injury to the considerable twig injury. exposed branches. In some cases one year Pouteria campechiana, canistel. Old trees were old plants were killed to the ground or to not injured; young grafted trees 5 years in the straw wrap. the field had some injury to the branches Myrciaria calliflora, jaboticaba. Plants in good but this was not as severe as in 1956 at condition and protected by larger trees had which time some of the plants were killed no injury. Plants in exposed places showed to the ground. some leaf burn and twig injury. Psidium guapva, guava. Large trees had leaf Phyllanthus emblica, emblic. Young plants in burn and twig injury but not as severe as dormant condition and without leaves had in 1956; other younger plants had consider some injury to the terminal twigs. able injury to the branches. Syzygium cumini, Java-plum. Some leaf burn 4. Species most severely injured. and twig injury observed on both old and Anacardium occidentale, cashew. Young plants young plants, mostly on those not in healthy were killed. condition. Annona squamosa (sugar-apple), A. reticulata Syzygium jambos, rose-apple. Some leaf burn (custard-apple), A. muricata (soursop), A on young plants. diversifolia (ilama), and A. cherimoya X A. Tamarindus indica, tamarind. Old plants were squamosa (atemoya), were all severely in unaffected but young plants in exposed jured and in several cases the plants were places showed some twig injury. killed. The soursops, even under the pro 3. Species showing moderate to severe tection of overhead trees, were killed back leaf burn and twig injury. half way. 344 FLORIDA STATE HORTICULTURAL SOCIETY, 1958

Annona montana, mountain soursop, had less field with no protection showed consider injury with only leaf burn and some twig able damage, some plants killed outright, die back. others nearly to the ground. Antidesma bunius, bignay. Old plants protected , lovi-lovi. Young plants by surrounding vegetation were not injured, killed. but those in exposed places had a number Melicocca bijuga, Spanish-lime. Two large of branches killed. This injury was not as trees with nearby protection of large spread severe as in 1956. At the Ft. Lauderdale ing candle-nut trees were not injured and, planting young plants were severely in in fact, produced a good crop of fruit this jured. year. Two large trees in a more exposed lo Calocarpum sapote, mamey sapote. Both old cation were killed nearly to the ground. At and young plants had considerable damage Ft. Lauderdale young plants suffered leaf to the branches, but it was less severe than burn and twig injury. in 1956. Muntingia calabura, capulin. Medium size Chrysophyllum caimito, star-apple. Old and trees were killed to the ground, even plants very large trees were severely damaged as with overhead protection. At Ft. Lauder well as younger plants in exposed places. dale plants showed leaf burn and twig in Eugenia malaccensis, Malay-apple. Two me jury. dium-sized trees even under the protection Pouteria caimito, abiu. Young plants in ex of larger trees were severely damaged. posed area were killed; those protected by Flacourtia cataphracta, paniala. Older trees neighboring plants showed very little dam in a protected location showed no damage, age. but younger trees in exposed places were Spondias cytherea, ambarella. Very large trees killed. were severely injured with large branches , governor's plum. Large killed. At Fort Lauderdale younger plants plants in protected locations were not in had considerable leaf burn and twig in jured. The thornless variety growing in the jury.

EFFECT OF BEDDING AND MULCHING ON LAKE EMERALD

GRAPES UNDER CULTURE ON SOUTH FLORIDA

FLATWOODS SAND

N. C. Hayslip and L. H. Stover1 indicate that rolling land was generally pre ferred. Authentic statements on this are found Historical—References to desirable vineyard as far back as 1894 when George W. Wright, locations, soil types and drainage are found chairman of the Standing Committee on frequently in literature on viticulture. Many Grapes of the Florida State Horticultural So vineyards in Europe are set on slopes and ciety said: "Seven years ago (1888) the plant hillsides, and not infrequently narrow vine ing of grape began quite largely in South terraces cling precariously to steep mountain Florida. A large acreage was planted mostly sides. Most of the successful grape plantings to White Niagara, and up to the last year in California, New York and Michigan are there were 500 acres in Orange County alone, established on either rolling or steeply sloped and at least half that amount in adjoining lands that are well drained. counties." Florida grape growers have long been in Following the remarks by Wright, a Mr. terested in topography and drainage, and ref Mott had this critical comment to make con erences in early bulletins and public reports cerning the vineyard site selection in that

1 Entomologist, Indian River Field Laboratory, Ft. Pierce, day: "They have picked out the land that and Assistant in Horticulture, Watermelon and.Grape Investi has been under water: land that was never gations Laboratory, Leesburg, respectively.