Proc. Ha. State Hort. Soc. 112:282-285. 1999.

A PEER REVIEWED PAPER

EFFECTS OF FOUR ELEMENTS ON COLOR, YIELD AND VASE LIFE OF TREE "FERN5 ( VIRGATUS)

R. H. Stamps and D. K. Rock sium, manganese, zinc) have on tree yield and posthar University of Florida, IFAS vest longevity. Mid-Florida Research and Education Center

2725 Binion Road Materials and Methods Apopka, FL 32703-8504 used in this experimentwere grown from seed Additional index words. Chlorosis, postharvest, tiki "fern", iron, sown 11 Jan. 1995 in 30.5 x 61 cm [12 x 24 inch] flats filled manganese, magnesium, zinc. with soilless growing medium (Fafard Mix #4, Conrad Fafard, Inc., Springfield, MA) and placed under clear plastic covers

Abstract. Tree "fern" is the second most popular cut foliage in an unshaded greenhouse. Seedlings were transplanted crop produced in Florida, but almost nothing is known about into 10-cm [4-inch] plastic pots filled with soilless growing its nutritional requirements. This crop frequently has prob medium (Vergro Container Mix A without trace element lems with chlorosis that can significantly reduce the yield of charges, Verlite Company, Tampa, FL). harvestable stems. Plants from seed were grown in a soilless One year after seeds were sown, plants were repotted to medium (Vergro Container Mix A without trace element charg 15-cm [6-inch] diameter nursery cans filled with the same es, Verlite Co., Tampa, FL) in 25.4-cm diameter plastic cans for soilless growing medium (Vergro Container Mix A without two years. Cans were held in a shadehouse covered with 60% trace element charges) and placed on black polypropylene light exclusion fabric and were watered with overhead irriga ground cloth in a shadehouse covered with 60% light exclu tion 3 times/week during the winter and daily the rest of the sion polypropylene shade fabric. Six months after repotting, year. N, P and K were supplied using 20-3-8.3 or 14-6.2-11.6 controlled-release fertilizers without micronutrients (Nutri- plants were potted up to 25.4-cm [10-inch] diameter nursery cote® 20-7-10, Plantco, Brampton, Ontario; Osmocote® 14-14- cans, again using the same soilless medium, and nutrient 14, The Scotts Company, Marysville, OH) at the rate of 2,928 kg treatments were initiated. Initial medium Fe, Mg, Mn, and Zn N per ha [2614 lbs N per acre] per year. All pots received boron, levels were 0.19,113, 0.05 and 0.02 mg-kg-1 [ppm], respective copper, and molybdenum but iron, magnesium, manganese, ly. Initial and final medium pHs were 7.1 and 6.8, respectively. and zinc were applied at varying rates from 0 to a maximum of N, P and K were supplied using controlled-release fertiliz 90, 336, 45 and 22 kgha 1yr1 [0 to 80, 300, 40 and 20 lbs/acre/ ers without micronutrients (Nutricote® 20-7-10, type 180, year], respectively. Micronutrient applications did not affect Plantco, Brampton, Ontario; Osmocote® 14-14-14, type 3-4 average stem weights, but yields (number and weight of month, The Scotts Company, Marysville, OH) at the rate of stems) were affected by Fe. Tissue content of the micronutri 2,928 kg N per ha [2,614 lbs N/acre] per year. All pots re ents increased with increasing application rate, especially for Mn. Chlorosis was most closely associated with low Mn con ceived the same amounts of boron, copper, and molybde tent (r = 0.7, P< 0.0001). Vase life of harvested stems was gen num, 0.56, 5.6, and 1.7 kg-ha^yr1 [0.5, 5, 1.5 lbs/acre/year], erally unaffected by treatments. respectively; but iron, magnesium, manganese, and zinc were applied at varying rates from 0 to a maximum of 90, 336, 45, Florida produces over 78% of all cut cultivated greens and 22 kg-ha^yr1 [0 to 80, 300, 40, and 20 lbs/acre/year], re grown in the United States (U.S. Dept. Agr., 1999). Tree spectively (Table 1). Sulfate sources of Fe, Mg, Mn and Zn "fern" {Asparagus virgatusBak.), also known in the trade as tiki were applied in 150 mL [4.4 oz] of water per pot. Monthly ap "fern", is the second most commonly grown cut foliage in plication of elements began 23 Sept. 1996 and continued for Florida (Stamps, 1994). Tree fern is an ornamental asparagus two years. No pesticides containing micronutrients were used related to edible asparagus and is, therefore, not a true fern. on this crop. Pots were arranged in a randomized complete Tree fern is a relatively new crop and almost nothing is known block design with Ox, 2x and 4x treatments replicated six about its nutritional requirements. Growers have reported times and lx rate replicated 24 times. problems with chlorosis (yellowing) of cladophylls (portions In winter, polyethylene film covering the shadehouse, of stems modified to function as ). While some of these combined with forced air heaters, maintained temperatures problems are probably caused by damage due to mites and above 4°C [39.2°F]. A solid set overhead irrigation system fungal pathogens, some may be due to micronutrient defi provided 1.2 cm [Vi inch] of water three timesa week when ciencies and/or toxicities. The purpose of this experiment the shadehouse was covered with polyethylene and daily dur was to determine what effects four nutrients (iron, magne- ing the rest of the year. One to three stems per (depending on availability) were harvested in the afternoon for vase life studies on 25 Florida Agricultural Experiment Station Journal Series No. R-07176. The Nov. 1996, 22 July 1997 and 31 Dec. 1997. Stems were bun authors sincerely thank Dr. Arvel Hunter and Agro Services International, dled according to treatment and held in the shadehouse in Orange City, FL for providing tissue analysis for this study. Mention of a prod temperatures from 27-34°C [80-94°F] until the entire experi uct does not constitute a recommendation or warranty of the product by the ment was cut (an average of one hour). Bundled stems were authors or the University of Florida Institute of Food and Agricultural Scienc es, nor does it imply its approval to the exclusion of other products that may immersed in water, wrapped in polyethylene film and stored also be suitable. in waxed, corrugated fiberboard cartons at 4.4°C [40°F] for

282 Proc. Fla. State Hort. Soc. 112: 1999. Table 1. Nutrient application rates (kg-ha'-yr1 [lb/acre/yr])'. iment, samples were taken for tissue analysis. Filtered wet di gested plant tissue extract was analyzed for Fe, Mn, Mg and Zn Application using atomic absorption spectrometry (Hunter, 1988). level Fe Mg Mn Zn Rate effects on tree fern growth and vase life were deter Ox 0 84 [75] 11.2 [10] 5.6 [5] mined for each element using regression and chi-square anal 22.4 [20] 0 11.2 [10] 5.6 [5] ysis (SAS Institute, Cary, NC). 22.4 [20] 84 [75] 0 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 0

lx 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] Results and Discussion 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] Yield {harvestable stems and average stem size). Yield response 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] (stem numbers and total fresh weight) to Fe application rates 2x 44.8 [40] 84 [75] 11.2 [10] 5.6 [5] was quadratic with the lowest yields of all nutrient treatments 22.4 [20] 168 [150] 11.2 [10] 5.6 [5] occurring at the Ox and 4x rates (Table 2). Iron application 22.4 [20] 84 [75] 22.4 [20] 5.6 [5] rates did not affect stem size (average stem weights). The re 22.4 [20] 84 [75] 11.2 [10] 11.2 [10] duced yield at the Ox Fe rate suggests Fe is necessary for pro 4x 89.6 [80] 84 [75] 11.2 [10] 5.6 [5] duction of harvestable tree fern stems. However, in a nutrient 22.4 [20] 336 [300] 11.2 [10] 5.6 [5] solution study in which edible asparagus {Asparagus officinalis 22.4 [20] 84 [75] 44.8 [40] 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 22.4 [20] L.) seedlings were grown without Fe, yield was not reduced (Benson and Paulsen, 1990). Iron deficiency symptoms were z0x, 2x and 4x treatments were replicated six times; lx treatments were rep observed but the relatively short duration of that solution licated 24 times. study (3 months) may have been insufficient for yield reduc tions to occur. The depression in yield at the 4x rate may have 14 days. Upon removal from the cooler, stems were recut 5 been due to the Fe interfering with the Mn for uptake (Brady, cm [2 inches] above the base and placed by treatment in glass 1990; Mills and Jones, Jr., 1996). After Fe at the Ox and 4x jars filled with deionized water in rooms that simulated the rates, the lowest yields were for Mn at those same rates and home/office environment. Room conditions were main possibly for similar reasons. However, Mg, Mn and Zn treat tained at 20 ± 2°C [72 ± 4°F] and 55% ± 5% RH, with 12 hours ments did not affect yield or stem size. The lack of response of light/day at 17 jimol-m^s-1 (107 ft-candles) provided by to added Mg may have been due, at least initially, to the incor cool white fluorescent lamps. Vase life was terminated when poration of dolomite (2.1 kg-nr3 [3.5 lb/yd3]) and vermicu stems showed chlorosis (yellowing), signs of desiccation lite (20% by volume) in the growing medium. Both dolomite (graying) and/or cladophyll drop. and vermiculite are sources of Mg (Nelson, 1998), although All saleable stems (dark green and >38 cm [15 inch] in the amount of Mg in vermiculite is small (Poole et al., 1981). length) were harvested on 29 Aug. 1997 and 29 Jan., 11 May, In addition, edible asparagus {Asparagus officinalis L.) seed and 5 Dec. 1998. Additional harvests of unmarketable stems lings grew just as well in Mg deficient (-90%) nutrient solu for biomass production determinations were conducted 18 tion as they did in the complete Hoagland solution (Benson Dec. 1996, 9 Sept. 1997, and 3 June 1998. The biomass har and Paulsen, 1990). This suggests that asparagus may require vests simulated the commercial practice of mowing off the relatively little Mg for normal growth. Lack of Mn and Zn did crop periodically to remove damaged stems to make harvest reduce shoot fresh weight in that solution study. The lack of ing easier. Number of stems and fresh weights were recorded detectable yield effects in this experiment was probably not at each harvest. due to these micronutrients being supplied from the growing On 5 May, 9 July and 23 Sept. 1997 and 22 Jan., 7 May, 28 media since Fe, Mn and Zn are available in only very low Aug., and 27 Oct. 1998, plants were rated visually using the amounts from the type of growing medium used in this exper scale 1 = necrotic, 2 = very chlorotic (white), 3 = chlorotic (yel iment (Stamps and Evans, 1997). Rather, it may have been low), 4 = light green, or 5 = normal dark green appearance. due to stored reserves in the plants and low nutrient require Only plants rated 5 were acceptable. At the end of the exper ments because of the small amount of foliage that it produc-

Table 2. Yield of marketable tree fern stems7 from plants treated with four nutrients for two years.

Element

Fe Mg Mn Zn

Fresh wt Avg. stem Fresh wt Avg. stem Fresh wt Avg. stem Fresh wt Avg. stem Rate Number (g) wt(g) Number (g) wt(g) Number (g) wt(g) Number (g) wt(g)

Ox 55 383 7.2 68 546 9.5 75 489 6.9 110 688 6.6 lx 87 555 6.9 87 555 6.9 87 555 6.9 87 555 6.9 2x 96 778 8.0 71 535 7.8 93 658 7.5 69 548 8.3 4x 44 358 7.8 96 730 8.0 66 465 7.2 79 604 8.0 Significance*1 linear ns ns ns ns ns ns ns ns ns ns ns ns * ** quadratic ns ns ns ns ns ns ns ns ns ns cubic ns ns ns ns ns ns ns ns ns ns ns ns zDark green stems at least 38 cm [15 inches] in length. yns> *} ** nonsignificant or significant at P< 0.05 or 0.01, respectively.

Proc. Fla. State Hort. Soc. 112:1999. 283

Peterson, J. C. 1982. Effects of pH upon nutrient availability in a commercial Stamps, R. H. 1994. [Corrected] Commercial cut foliage production acreage. soilless root medium utilized for floral crop production. Ohio Agr. Res. Univ. of Fla., Inst. of Food and Agr. Sci., Fla. Coop. Ext. Serv. Cut Foliage and Devel. Center, Res. Cir. 268. Grower 9 (3/4) :4. Poole, R. T., C. A. Conover andj. N. Joiner. 1981. Soils and potting mixtures. Stamps, R. H. and M. R. Evans. 1997. Growth of Dieffenbachia maculata 'Cam- In]. N. Joiner (ed.). Foliage Plant Production. Prentice-Hall, Englewood ille' in growing media containing sphagnum peat or coconut coir dust. Cliffs, NJ. HortScience 32:844-847. Salisbury, F. B. and C. W. Ross. 1978. Plant Physiology. 2nd ed. Wadsworth U.S. Dept. Agr. 1999. Floriculture crops, 1998 summary. United States Dept. of Publishing, Belmont, CA. Agr., National Agr. Statistics Serv., Agr. Statistics Board, Washington, DC.

Proc. Fla. State Hort. Soc. 112:285-290. 1999.

SOIL FUMIGANT AND HERBICIDE COMBINATIONS FOR SOILBORNE PEST CONTROL IN CALADIUM

James P. Gilreath plication of oryzalin provided good weed control for all fumi University of Florida, IFAS gant- treated plots into mid fall, after which time the grower was not concerned about weed control. Root-knot nematodes Gulf Coast Research and Education Center (Meloidogyne sp.) were not found in the tubers from any fumi Bradenton, FL 34203 gated plot at harvest nor in soil samples from any plot during the season. Fusarium sp. was found in all of the tubers at Robert McSorley planting and at harvest. Although Erwinia, Fusarium, Pythium Dept. ofNematology and Entomology and Rhizoctonia were found in most of the tubers, no differ Gainesville, FL 32611 ences were found in incidence of infestation due to any treat ment. There was no difference in tuber production for any size grade, except jumbo; significantly more jumbo tubers were Robert J. McGovern produced in plots treated with 1,3-dichloropropene + chlorop Gulf Coast Research and Education Center icrin with metolachlor at planting followed by oryzalin in mid Bradenton, FL 34203 summer. Chloropicrin + 1,3-dichloropropene out produced all other fumigants for jumbos and no difference was found in Additional index words. Methyl bromide, metham, 1,3-dichlo- jumbo production with methyl bromide or metham + chloropi ropropene, chloropicrin, metolachlor, oryzalin, weed con crin or where no fumigant or herbicide was applied. No differ trol, nematodes, soilborne disease. ences in the tuber production index were evident with any treatment.

Abstract. Soil fumigant and herbicide combinations were inves tigated as replacements for methyl bromide in 'Red Frill1 cala- Greater than 95% of the world's production of caladium dium (Caladium x hortulanum Birdsey) tuber production in tubers occurs in a small geographical area near Lake Placid, 1998 on a sandy muck soil at a commercial farm in Lake Placid, Florida. Most of the production is on muck or high organic FL. Treatments consisted of methyl bromide:chloropicrin matter soils. Soilborne pest control is a major problem for pro (90/10%), 1,3-dichloropropene + chloropicrin, metham + chlo ducers (Overman and Harbaugh, 1982). Pests range from ropicrin and a nontreated control. Plots treated with 1,3-dichlo ropropene or metham received soil surface sprays of weeds to root-knot nematodes and soilborne diseases, such as metolachlor at planting and oryzalin about 7 weeks later. Plots Fusarium. Early work by Rhoades (1964) demonstrated the treated with methyl bromide received only oryzalin, whereas utility of hot water treatment as a means of eliminating root- the nontreated controls received no herbicide during the ex knot nematodes from tubers. Additionally, he studied the re periment and were handweeded as needed. Initial plant stand sponse of caladiums grown in muck soil to soil fumigants in was not affected by treatment. Plant vigor was higher in methyl the presence of root knot nematodes and found that soil fumi bromide treated plots on 30 July; but by 6 October plants were gation increased yield only in cases where root-knot nematode just as vigorous in plots treated with 1,3-dichloropropene + populations were high. A mixture of dichloropropene, dichlo- chloropicrin as they were in areas fumigated with methyl bro ropropane and methyl isothiocyanate (Vorlex) and 1,3-dichlo mide. Early control of weeds was good with those treatments ropropene + 1,2-dichloropropane (D-D) provided good which received metolachlor, but treatment with methyl bro mide alone allowed an early infestation of crabgrass (Digitaria control of root-knot with increased tuber production. A later ciliaris (Retz.) Koel.) and pigweed (Amaranthus viridis L.). Ap- study by Overman and Harbaugh (1982) demonstrated the ef ficacy of methyl bromide in muck soils when combined with tissue cultured stock; however, when used with standard com Florida Agricultural Experiment Station Journal Series No. R-07070. This mercial tuber stock, there was no response to methyl bromide research was supported in part by the Florida Caladium Growers' Box Tax fumigation. In sandy soils, methyl bromide soil fumigation im Fund for which the authors are grateful. The authors also wish to thank Bates proved tuber production regardless of tuber source. The au and Sons and Daughters Caladiums for their support and help on this project. This paper reports results of research and should not be construed thors also observed no effect on soilborne disease control in as a recommendation by the authors or the University of Florida. the tubers at harvest as a result of fumigation, especially with

Proc. Fla. State Hort. Soc. 112: 1999. 285