Flea beetles (Epitrix spp.) are often a pest in seedling beds. Bed sterilization, as well as burning or clearing vegetation around the beds, enhances control. Also, covering the beds with tobacco cloth or similar cover, with a minimum 25 strands per inch, will provide a suitable physical barrier. Histori- cally, cryolite and 1% rotenone dusts have been used to control flea beetles. For fur- ther information, ask for ATTRA’s Flea Bee- tle: Organic Control Options.
Rotations: Growing tobacco in a planned rotation with other crops is a good way to manage fertility and suppress many weeds, insect pests, and plant diseases— particularly black root rot (Thielaviopsis basicola), nematodes, and bacterial wilt (Pseudomonas solanacearum). Since the eco- nomic value of tobacco is very high, it is at the top of the pecking order with regard to planned rotations, and the welfare of other crops is of secondary concern.
As a rule, tobacco does very well following corn, cotton, and small-grain crops. Leaf quality usually is reduced following legumi- nous forage crops and cover crops because of excessive soil nitrogen and organic matter. Quality also has been observed to vary following legume crops of peanuts, crotolaria, soybeans, cowpeas, velvetbean, and lespedeza.
To control bacterial wilt, a four- or five- year rotation is suggested, avoiding sus- ceptible crops such as tomatoes, peppers, and peanuts.
Tobacco does well on virgin soils and soils previously in grass or grass-legume sods. Wireworms (Limonius spp.) can, however, be a problem in sod soils and remain a sig- nificant pest to crops up to five years after the sod is broken.
Cultivation and Fertility: Good field preparation should include a well-prepared seedbed, free of clods and weeds. Trans- plants are set out in rows, which may vary from three to four feet in width, with plant spacing 18–36 inches apart in the row.
Factors such as tobacco type and variety, soil type, and equipment determine the precise spacings used.
Supplementary fertilization using standard commercial fertilizers is the routine practice on conventionally managed farms. Nitro- gen is managed carefully to avoid exces- sive growth and accumulation of nitrogen compounds in the leaves. Phosphate also is managed carefully, as excessive amounts in the leaves alter burning characteristics of the leaf. High potash levels, on the other hand, are desirable. Adequate soil potash is also important in suppressing angular leaf spot (P. angulata) and bacterial leaf spot (P. tabaci). Chlorine-based fertilizers, how- ever, such as potassium chloride, cannot be used, as they too reduce burning quality of the tobacco. Supplementary fertiliza- tion commonly includes a source of mag- nesium. Inadequate levels of soil magne- sium encourage incidence of a nutritional disorder called “sand drown.” About 24–35 lbs/acre of soluble magnesium is considered adequate for most fields. Either dolomitic lime or sulfate of potash- magnesia is commonly used to supply magnesium in both conventional and organic cropping systems.
Soil pH should be maintained in the slightly acidic range (5.5–6.5) with an available calcium level five times that of magne- sium.(6) At higher pH levels, the incidence of black root rot increases.
Manures have historically been used in tobacco production, with rates of supple- mentary fertilizers reduced accordingly. Dark tobacco, especially, responds well to fertilization by manures, though it is advisable that they be applied and incor- porated the previous fall. Application of animal manures to flue-cured and other lighter tobaccos is much more risky. Dr. W.D. Smith of North Carolina State Coop- erative Extension has advised that manures be used on corn and other crops in rotation, to minimize any possible side effects on the tobacco crop.(7) ATTRA provides addi- tional guidelines for manure use in Manures for Organic Crop Production.
A s a r u l e tobacco does very well following corn, cotton, and small- grain crops. ,