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Tropical Root Crop Production in Florida

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Material Information

Title: Tropical Root Crop Production in Florida
Physical Description: Fact sheet
Creator: Lamberts, Mary L.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Notes

Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status: Published
General Note: "January 2012"
General Note: "HS965"

Record Information

Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00003484:00001

Permanent Link: http://ufdc.ufl.edu/IR00003484/00001

Material Information

Title: Tropical Root Crop Production in Florida
Physical Description: Fact sheet
Creator: Lamberts, Mary L.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Notes

Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status: Published
General Note: "January 2012"
General Note: "HS965"

Record Information

Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00003484:00001


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Page 345 Chapter 24. Tropical Root Crop Production in FloridaM.L. Lamberts and S.M. Olson INTRODUCTION There are four main tropical root crops produced in Florida. In order of acreage, these are: tropical sweetpotato (a.k.a. batatas, boniato or camote), taro (a.k.a malanga islea or malanga), tannia, (a.k.a. malanga or yauta), and cassava. The following table alphabetically lists the botani cal families, scientific names and both English and Spanish common names for these crops. BRIEF DESCRIPTIONS OF TROPICAL ROOT CROPS Cassava a short-lived perennial tropical shrub growing 3 to 12 ft. tall. Adventitious roots arise from stem cuttings. They vary in shape from long and slender to globose and enlarge during the starch storage process. Stems are woody and variously branched. Simple leaves, generally dark green, have palmate lobes. Taro produces an enlarged edible corm. Its leaves are peltate and when viewed from the abaxial surface resemble a heart with a heavily pigmented spot at the point where the petiole is attached to its adaxial surface. Tannia produces an enlarged corm that may or may not be edible. Underground club-shaped cormels are produced during later growth stages. Leaves have long peti oles and broad sagittate lamina. Tropical sweetpotato resembles other sweetpotatoes grown in the United States, but the skin ranges in color from light pink to a deep wine red and the flesh is white and starchier than yellowor orange-fleshed cultivars. VARIETIES Cassava varieties are often separated based of their cyanogenic glucoside (HCN) content into either low HCN, a.k.a. sweet, or high HCN, a.k.a. bitter, types. The term bitter comes from a bitter flavor that is commonly believed to accompany the HCN. No named varieties are currently known in southern Florida. Senorita was locally popular in the 1980s and attempts were made to introduce the CIAT variety Mantiqueira at that same time because it was able to produce acceptable yields even with high levels of rootknot nematode. The range of local genopytes covers a few unnamed clones that have been imported from various Caribbean basin countries. Federal regulations prohibit further importation of cuttings or botanical seed. Taro Malanga Islea, produces one large whitefleshed central corm; a few unnamed Polynesian types are grown for the Asian market. Tannia South Dade White, producing white-fleshed cormels; Malanga Amarilla, producing a yellow-fleshed edible corm; and Vinola, producing purple-fleshed cormels. Tropical sweetpotato Picadito is the main variety grown in Miami-Dade County. It has deeply lobed leaves and wine colored skin. PLANTING AND SEEDING Cassava In Miami-Dade County, theoretically it can be planted year round (Table 1). Normally, the planting is done in the early spring due to slow early growth and the possibility of a winter frost. Stem cuttings 4" long are selected from the lower mature sections of healthy plants and planted horizontally, 3-6" below the soil surface in shallow Rockdale soils. Cuttings are planted by hand in furrows spaced 48 apart with an in row spacing of 24 ". 2012-2013 Table 1. Planting information for cassava. Planting datesMiami-Dade Florida Year-round (mainly February to April) Planting informationDistance between rows (in) 48 Distance between plants (in) 24 Planting depth (in) 3 4 Propagules needed per acre 5,445 Days to harvest from planting 270 360 Plant populations (acre) 5,445

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Vegetable Production Handbook Page 346 Since unrooted cuttings are sensitive to water loss, the field should be irrigated soon after planting. Taro & Tannia In Miami-Dade County, both crops can be planted year round Table 2. Normally, the colder winter months are avoided due to slow growth and susceptibil ity to frost. For tannia, the top portion of the mother corm is used for planting., For taro, the smaller unmarketable side shoots are used. Both are planted by hand in furrows spaced 48" apart with an in row spacing of 24". Planting in other parts of Florida should consider dates of last and first frosts, while allowing for a 9 14 month crop. Tropical sweetpotato In Miami-Dade County, this crop can be planted year round, though planting is some times delayed if extremely cold weather has been forecast. As with orangeor yellow-fleshed varieties, vine cuttings are used for planting. Planting in other parts of Florida should consider dates of last and first frosts.FERTILIZER & LIME Cassava Apply all P2O5 micronutrients, and 25 to 50% of N and K2O in a band along the planted row one to two months after planting. Sidedress the remaining N and K2O by banding them on the side of the bed four months after planting as a layby. Specific fertilizer recommendations for Rockdale soils are not available due to lack of a reliable and readily available soil analysis procedure for this soil type. In general, cassava has a medium require ment for N, P2O5 and K2O. Since the soils in Miami-Dade have a high pH, liming is not needed. There are no remedi ation materials for the high pH condition, though chelated forms of micronutrients such as Fe, Mg, Mn and Zn can be applied to treat deficiencies. Taro & Tannia Apply all P2O5 micronutrients, and 25 to 50% of N and K2O in a band along the planted row one to two months after planting. Sidedress the remaining N and K2O by banding them on the side of the bed four months after planting as a layby. Specific fertilizer recom mendations Rockdale soils are not available due to lack of a reliable and readily available soil analysis procedure for this soil type. In general, taro and tannia have medium to high requirements for N, medium to low requirements for P2O5 and medium requirements for K2O. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. IRRIGATION Cassava has relatively low requirements for irrigation. But, during active growth stages it must be irrigated when extended dry spells occur. Water requirements and subse quent irrigation requirements are reduced during the last few weeks of growth. This usually coincides with the dry season when cassava is most likely to be affected by mites, a situation which can be helped by using overhead irriga tion since it increases humidity in the field. Taro & Tannia grow best when the soil is maintained moist, but not wet, at all times. Proper water management is essential for optimum corm and cormel sizing. Water requirements and subsequent irrigation requirements may be reduced during the last few weeks of growth. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. CULTURAL PRACTICES Soil Preparation Cassava grows best when the soil is turned 2 to 3 months before planting. Plowing early helps rot plant debris and reduce some nematode and disease problems. Soils in Miami-Dade County (except for marl soils) should be scari fied or rock plowed prior to planting to improve drain age and increase available soil depth. For cassava, marl soils will always produce the best-shaped and best-looking storage roots. However, these soils are prone to flooding, making them less desirable for cassava production. Plants grown on Rockdale soils must be irrigated during periods of dry weather to avoid reduced yields. Wet weather for extended periods can cause leaching of N and K, requiring the addition of more fertilizer. More frequent applications of smaller amounts of fertilizer per application are sug gested for Rockdale soils. In general, fields that have not produced a crop of cassava in the last 2 to 3 years are pre ferred. Avoid fields that have very high nematode popula tions or use a resistant variety if one is legally available. Table 2. Planting information for tannia and taro. Planting datesMiami-Dade Florida Year-round (mainly February to April) Other areas (after danger of frost has passed, but early enough to avoid frost or freezing before harvest.Planting informationDistance between rows (in) 48 Distance between plants (in) 24 Planting depth (in) 3 4 Propagules needed per acre 5,445 Days to harvest from planting 270 360 Plant populations (acre) 5,445

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Chapter 24: Tropical Root Crop Production in Florida Page 347 Taro & Tanier grow best when the soil is turned 2 to 3 months before planting. Plowing early helps rot plant debris and reduce some nematode and disease problems. Soils in Miami-Dade County (except for marl soils) should be scarified or rock plowed prior to planting to improve drainage and increase available soil depth. For tannia, marl soils produce the best-shaped and best-looking cormels. These soils are preferred if supplemental irriga tion cannot be supplied. Plants grown on Rockdale soils must be irrigated during periods of dry weather to avoid reduced yields. Wet weather for extended periods can cause leaching of N and K, requiring the addition of more fertilizer. More frequent applications of fertilizer using smaller amounts each time are suggested for Rockdale soils. In general, fields that have not produced a crop of tannia or taro in the last 2 to 3 years are preferred. Avoid fields that have very high nematode populations. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Bedding Cassava, Taro & Tannia Plants are established in rows on flat land. During the cultivation process, ridges are formed down the rows of plants. Ridges provide a place for storage organ formation, improve drainage and facilitate harvesting. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Table 3. Fungicides approved for disease management on cassava, taro and tannia. Chemical Name Rate/acre to Harvest CommentsActinovate AG 12 oz 0 Biological material Azoxystrobin (several brands) See label 14 See label for maximum use rate and restrictions Apron XL LS 0.64 oz/cwt. 0 Apply to seed pieces Evito 480 SC 3.8 oz 7 See label for maximum use rate and restrictions Fluoxastrobin (several brands) See label 7 See label for maximum use rate and restrictions Forum 6 oz 30 For use on Taro only Kaligreen Fungicide 2.5-3.0 lbs 0 See label for maximum use rate and restrictions Maxim 4 FS 0.16 oz/cwt. 0 Apply to seed pieces Mefenoxam (several brands) See label See label for maximum use rate and restrictions Metalaxyl (several brands) 4 pts 0 apply preplant or shortly after planting Oxidate 1/100 0 Potassium phosphite (several brands) See label 0 Presidio 4 oz 7 See label for maximum use rate and restrictions Pyraclostrobin See label See label for maximum use rate and restrictions Quadris Top 14 oz 1 See label for maximum use rate and restrictions Quash 4 oz 1 See label for maximum use rate and restrictions Reason 500 SC 8.2 oz 14 See label for maximum use rate and restrictions Regalia 0.5-1.0% v/v dilution 0 See label for specific use directions Revus 8 oz 14 See label for maximum use rate and restrictions Ridomil Gold EC See label apply preplant or shortly after planting Scala SC 7 oz 7 Serenade ASO, MAX See label 0 Soilgard 12G 2 10 lbs See label for specific use directions Sonata 2-4 qts 0 Switch 62.5 WG 14 oz 7 See label for maximum use rate and restrictions Trilogy 2 gal 0 Uniform Fungicide 0.34 oz/1000 feet of row Apply in furrow at planting

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Vegetable Production Handbook Page 348Cover Crops Taro & Tanier Cover crops are not recommended immediately after tannia and taro production. Cultivation is needed after harvest to prevent feral plant establishment. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Disease Management Cassava There are several virus diseases of cassava. However, none have been reported to occur in the United States. Systemic diseases are also common in cassava. Planting material should pass through a phase of tissue culture and thermo therapy. Cassava bacterial blight (see PP-40: edis.ifas.ufl.edu/VH053) and Cercospora leaf spot are known disease problems in the United States. When pathogens are present, yields can be reduced by 50% if healthy, pathogen-free or disease resistant cuttings are not used. This emphasizes the need to select clean, healthy planting material. Since cassava is vegetatively propagated, virus and other systemic diseases can be carried from one planting to another in the planting material. Effective dis ease control for cassava is based on prevention. Most of the important diseases are caused by pathogens that can be easily spread by wind, rain and workers or are capable of spreading systemically through the plant. It is usually not possible to restore the health of an affected plant once the disease can be detected. A crop rotation of at least 3 years is an important means of controlling diseases. Chemicals approved for management of cassava diseases are shown in Table 3. Taro & Tannia Dasheen mosaic virus (see PP-40: edis. ifas.ufl.edu/VH053) and systemic diseases are common in tannia and taro. Planting material should pass through a phase of tissue culture and thermo therapy. Bacterial leaf blight (see PP-40: edis.ifas.ufl.edu/VH053) and root rot are two other maladies affecting tannia. Taro has few known disease problems in the United States. Losses due to these diseases have not been documented, but they can be significant. Genetic resistance to dasheen mosaic virus and root rot diseases is not well documented. Effective disease control for tannia and taro are based on prevention. Most of the important diseases are caused by root pathogens or are capable of spreading systemically through the plant. It is generally not possible to restore the health of an affected plant once the disease can be detected. Since taro and tannia are vegetatively propagated, virus and other systemic diseases can be carried from one planting to another in the propagules. A crop rotation of at least 3 years is an important means of controlling diseases. Chemicals approved for management of tannia and taro diseases are listed in Table 3. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Insect Management Cassava Whitefly, spider mites, shoot fly and tomato hornworm are occasionally observed. Since there is no documentation of economic loss due to these pests, pesti cides (Table 4.) are not normally used. Although mites can cause leaf drop, they are normally not present in significant numbers until the winter months when the plants nearing harvest. Keeping fallowed fields free of feral plants is rec ommended. Taro & Tannia Diaprepes root weevil is the main pest of tannia. Larval feeding causes physical damage to the cormels, causing them to be placed in a lower grade. Whitefly, thrips, and salt marsh caterpillar are occasionally observed. However, there is no documentation of economic loss due to these pests. Resistance is not known to any of these pests. Keeping fallowed fields free of feral plants is recommended. Table 4 lists chemicals labeled for taro and tannia. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Nematode Management Cassava can be damaged by root-knot nematodes. It may cause stunting and yield loss; root-knot nematodes in the storage roots may cause cracking or internal dark lesions that severely reduce the value of the product. The only step to minimize nematode injury to cassava is to include crop rotation unless nematode-tolerant varieties can be introduced legally. Taro & Tannia Taro is frequently damaged by rootknot nematodes. Nematodes may cause stunting and yield loss; root-knot nematodes in the corms may cause crack ing or internal dark lesions that severely reduce the value of the product. Several steps to minimize nematode injury to taro include crop rotation and use of nematode-free propagules. Using a field immediately after a crop that has legally been treated for nematodes may reduce injury. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. EPA Crop Grouping and lables The Environmental Protection Agency establishes tolerances for pesticide residues in raw agricultural commodities. The crop grouping scheme allows tolerance to be established on a large number of commodities from research on certain specific crops in that group. The tropi cal root crops fall under the Tuberous and Corm vegetable subgroup of the Root and Tuber Vegetable group. This means that if a label states that the pesticide is labeled for root and tuber crops, or for tuberous and corm vegetables, it may legally be applied to the tropical root vegetables including: arracacha, arrowroot, Chinese arti-

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Chapter 24: Tropical Root Crop Production in Florida Page 349 Table 4. Selected insecticides for insect management on cassava, taro and tannia. Chemical Name Rate/acre Minimum Days to Harvest Comments NotesAbamectin (several brands) 8.0 16.0 oz 14 Colorado potato beetle, Liriomyza leafminer, potato psyllid, spider mites See label for detailed use instructions Actara 1.5 oz 14 leafhoppers Assail 30 SG, 70 WP see label 7 aphids, leafhoppers, flea beetles Avaunt 6 oz 7 various caterpillars Azadirachtin (many brands) see label 0 whiteflies, hornworms Battalion 0.2 EC (see label) 3 various caterpillars, pea aphid, flea beetles, leafhoppers, plant bugs Baythroid XL 2.8 oz 0 various caterpillars, flea beetles Beleaf 50 SG Insecticide 2.0 2.8 oz 7 aphids and plant bugs See label for detailed use instructions. Plants back restrictions apply for unlabeled crops Bifenthrin (various brands) See label See label cucumber beetles, wireworms, flea beetles, white grubs may be applied to soil prior to planting Bacillus thuringiensis (various brands) see label 0 various caterpillars See individual labels. Note: there are 2 strains, aizawai and kurstaki Carbaryl (various brands) See label 7 Colorado potato beetle, various caterpillars, stink bugs, lace bugs Coragen 3.5 5.0 oz 14 Beet armyworm, western striped armyworm See label for detailed instructions Deltamethrin (various brands) See label 3 various caterpillars, flea beetles, green peach aphid Endigo ZC 4.5 oz 14 Fleabeetles, leafhoppers, various caterpillars, grasshoppers, stink bugs, aphids, leafminers, whiteflies See label for detailed instructions Fulfill 2.75 oz 14 aphids, whiteflies Hero, Hero EW See label 21 Grasshoppers, various caterpillers, leafhoppers, Colorado potato beetle, sweet potato weevil (adult) See label for detailed instructions Imidacloprid (many brands) see label 125 aphids, leafhoppers, whiteflies soil application at planting Imidacloprid (many brands) see label 7 aphids, leafhoppers, whiteflies foliar applied Intrepid 2F 6-16 oz 14 armyworms, cutworms, loopers, webworms Knack Insect Growth Regulator 8 oz 3 Whiteflies Section 24 (c) label; must be in users possession at time of use Lambdacyhalotrin (many brands) See label See label Cutworms, leafhoppers, caterpillars, various beetles, grasshoppers, psyllids, stinkbugs, plant bugs, weevils See label for detailed use instructions Leverage 2.7 3.5 oz 7 Whitefly, chili thrips, stink bugs, Thrips palmi See label for detailed instructions Leverage 360 2.8 oz 7 Aphids, various caterpillars, flea beetles, leafhoppers, sweet potato weevil See label for detailed instructions M-Pede 1-2% solution 0 Aphids, whiteflies, thrips, mites, leafhoppers See label for caution information, OMRI approved material Movento 5.0 5.0 oz 7 Aphids, psyllids, whiteflies See label for detailed use instructions Mustang (various) See label 1 Cutworms, various caterpillars, cucumber beetle, fleabeetle, leafhoppers, weevil, aphids, tarnished plant bug See label for detailed use instructions Oberon 2SC 8-16 oz 7 whiteflies two spotted spider mites Oil, insecticidal 1-2 gal/100 gal water 1 leafminers, mites, whiteflies Platinum 5.0 8.0 oz See label Aphids, flea beetles, leafhoppers, whiteflies See label for detailed use instructions

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Page 350 Vegetable Production Handbook choke, Jerusalem artichoke, edible canna, cassava, chayote root, chufa, dasheen (taro), ginger, leren, sweet potato, tanier, taro, tumeric, yam bean, and true yam. Check the labels of the pesticides to see if the crop group is listed. Weed Management See Table 4, Chapter 22, Sweetpotato Production in Florida. Taro & Tannia are long-season crops. Control of weeds during the extended production period can be diffi cult. Early season competition of weeds is extremely detrimental to crop yield, so a major emphasis on weed control should be made during this period. Growers must plan a total program that integrates mechanical and cultural meth ods of weed control with the use of herbicides. Cultivation is an effective way to manage weeds early in the season. Hilling blades can uproot many annual weeds that have emerged since the last cultivation. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Harvesting / Packing Cassava Unlike most vegetable crops, cassava does not have a definite stage where it is classified as mature since plants will continue to grow as long as there are green leaves. The crop should be harvested nine to 12 months after planting when it has produced the highest percentage of edible storage roots of the desired size. The crop should be harvested before or soon after killing frosts. Critical temperatures for root damage in the field are not known. Care should be taken to avoid skinning roots dur ing the harvesting process. Once harvested, the roots are very perishable. Waxing of the roots is a common practice to improve shelf life. Taro & Tannia Unlike most vegetable crops, taro and tannia do not have a definite stage where they are classi fied as mature since plants will continue to grow as long as there are green leaves. The crop should be harvested when it has produced the highest percentage of the edible portion (cormels or corms) of the desired size. Tannia and taro should be harvested before killing frosts. Critical tem peratures for corm and cormel damage in the field are not known. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Crop Rotation Cassava, Taro & Tannia There are usually not as many root-knot nematodes where the preceding crop was a grass or small grain. Most vegetable crops are among the worst crops to precede cassava, from the standpoint of Vegetable Production Handbook building up hazardous Chemical Name Rate/acre Minimum Days to Harvest Comments NotesRadiant SC See label 7 Colorado potato beetle, European corn borer, armyworms, Liriomyza spp. leafminers, loopers, thrips See label for detailed use instructions Renounce 20WP 1-3.5 oz 0 cutworms, loopers, flea beetles, Respect 4 oz 1 Flea beetles, various caterpillars, leafhoppers, vegetable weevil, grasshoppers, Colorado potato beetle See label for detailed instructions leafhoppers Soap, insecticidal 1-2 gal/100 gal water 0 aphids Spinosad (various brands) See label 7 Various caterpillars, dipteran leaf miners, thrips See label for detailed use instructions Swagger 15.4 oz 21 Flea beetles, sweet potato weevil, various caterpillars, potato psyllid, Colorado potato beetle See label for detailed instructions Tombstone, Tombstone Helios See label 0 Potato psyllid, sweet potato weevil (adult), flea beetles, various caterpillars, Colorado potato beetle See label for detailed instructions Voliam Flexi / Xpress See label 14 Flexi: Aphids, beet armyworm, looper, Colorado potato beetle, European corn borer, flea beetles, potato leafhopper Xpress: above plus cutworms, leafhoppers, various caterpillars, various true bugs, thrips, beetles See label for detailed use instructionsTable 4. Continued.

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nematode populations. Sweet corn may be the best rotation crop of the vegetables. Fields that have been planted to okra as a preceding crop should be avoided since rootknot nematode populations tend to build up in okra fields. Do not plant any of these crops in the same field in successive years. Tropical sweetpotato see Chapter 22, Sweetpotato Production in Florida. Flood Tolerance Cassava plants may tolerate a few days of mild flooding. However, storage root quality is significantly reduced and planting material may be lost if flooding is severe. Taro & Tannia Taro (malanga islea) is more flood tolerant than tannia. The variety grown in Miami-Dade does not tolerate continuous flooding. Tannia plants will tolerate a few days of flooding. However, cormel quality is significantly reduced, due to wart like growths that form on the cormels. Other Information Cassava HCN: Fresh roots and leaves are toxic due to the presence of free and bound HCN. The total HCN content varies considerably with variety, environment and plant age. Levels in the peel, peeled root and leaves ranged from 5 to 77, 1 to 40 and 0.3 to 29 mg/100 g (fresh wt.), respectively. Cooking the leaves or roots and changing the cooking water are methods for reducing HCN concentra tions. Roots should always be peeled prior to cooling. Toxicity from cassava may develop when considerable quantities are consumed over a period of time. This is par ticularly true if the prepared cassava has high HCN concentrations and the diet is poorly balanced nutritionally. Taro & Tannia Nematode-free planting material: Do not take nematodes or other soil borne problems to the field by planting contaminated plants. If plants must be propagated from suspect soil, use cleaned cuttings to avoid carrying potential problems into the field. Vegetable Production Handbook Page 351