WAX AND RELATED COATINGS 
FOR HORTICULTURAL PRODUCTS 
-- A BIBLIOGRAPHY -- 
By 
R. E. Hardenburg, research horticulturist + 
INTRODUCTION 
This list of 292 references was prepared to 
aid research workers contemplating further 
work on use of wax, wax emulsions, or related 
coatings for horticultural products, It also is 
intended as a correspondence aid and to 
answer other requests for information on the 
subject. No doubt some significant contribu- 
tions on waxing fruits, vegetables, andnursery 
stock have been overlooked, as titles often do 
not tell the full scope of the investigations or 
of products tested. 
The technology of using wax to prolong the 
life of fruits is not new. The Chinese experi- 
mented with molten wax dips for oranges and 
lemons in the 12th and 13th centuries (1). 
They discovered that this caused the fruit to 
ferment. They then developed a method of 
applying wax with brushes. As better results 
were obtained, they experimented with other 
fruit. Waxing of citrus has now become com- 
monplace. The possibilities of waxing vege- 
tables, apparently was first reported in 1935 
by Harvey and Landon (216), who showed that 
water losses from winter squash could be 
markedly reduced by waxing. However, toma- 
toes and some other vegetables were probably 
waxed earlier than this. 
Horticultural crops may be waxed for a 
variety of reasons, but most commonly they 
are waxed to retard evaporation andtranspira- 
tion losses from tissues that lead to wilting, 
1 Horticultural Crops Research Branch, Market Quality 
Research Division, Agricultural Research Service, U,S, 
Department of Agriculture, Beltsville, Md, 
2Numbers in parentheses refer to specific references 
given in the report, 
shriveling, and general shrinkage. Excessive 
moisture loss makes products unattractive to 
consumers and survival of nursery stock is 
impaired. The wax coating should not be so 
thick as to unduly interfere with respiration, 
ripening, or other metabolic processes as 
injury may result. However, root crops such 
as rutabagas, with a relatively low res- 
piration rate, may receive a fairly thick 
paraffin coating and remain uninjured in stor- 
age. 
Some horticultural crops are waxed to 
improve their luster or natural appearance, 
Others are coated in an attempt to prevent 
deterioration, such as decay, physiological 
breakdown, sprouting, aging, and color changes. 
For this purpose other chemicals such as 
fungicides, bactericides, growth regulators, 
and senescence inhibitors may be incorporated 
in the wax formulation. Citrus is often treated 
with a high gloss fungicidal wax for three 
benefits; To reduce moisture loss, to retard 
decay, and to improve appearance (103), For 
still other fruits and vegetables, a wax coating 
may serve as a lubricant to reduce scarring 
or chaffing during marketing. 
At least eight methods of applying wax have 
been developed to obtain desired results. Some 
involve fairly elaborate equipment as 
illustrated by Hartman and Isenberg (182). The 
wide range in texture of surface tissues of 
different products (oranges, peppers, canta- 
loups, rose bushes) helps explain why no single 
application method or type wax is best for all. 
Some products have a good natural protective 
skin and would benefit little, if any, from added 
wax. Application methods include dipping 
