Midwest Vegetable Guide - 2022 - 248

Rhubarb - Diseases
emerge. Use with another herbicide. Some varieties may be
sensitive to Zidua. REI: 12-hour. HRAC 15.
Rhubarb - Horticulture
Major update by Ben Phillips, Liz Maynard - Oct 2020
Reviewed by Liz Maynard - Aug 2021
Crop Description
Rhubarb is a plant of unknown European origin, but most
commercial varieties are hybrids, Rheum x hybridum, that
will not produce true from seed. Variety names have been
lost, confused, and rebranded over the years. There are only a
handful of varieties that can be sourced in the United States,
and the varieties most grown commercially are Canada Red,
MacDonald, Sutton, and Victoria - all red-stalked varieties.
There are more productive varieties that produce green stalks,
but red-stalked varieties are more popular at market and are
more amenable to a process called " forcing " . After two years
of unharvested growth, plants can begin to be annually
harvested in the field for 3 to 8 productive years.
Alternatively, after three years of unharvested growth, plants
can be dug in late fall or early winter and stored in dark
indoor facilities where they are sprouted early for a lucrative
late winter and early spring harvest, after which the roots are
exhausted and discarded. Victoria is the most reliable forcing
variety, and the most widely available.
Planting and Spacing
Use only young, healthy crowns having preferably 2 or 3
buds. Rows 5 to 6 feet apart. Set crowns 3 feet apart in
shallow furrows so crowns will be 2 inches below surface.
Break off flower stalks to maintain a strong root system year
after year. Infertile soil, extreme heat or cold, drought, or
long days that expose plants to too much light may cause
bolting, and older plants bolt more. A productive planting can
be maintained for 3 to 8 years.
For forcing, crowns are placed in a dark room with about 1
square foot per crown on an open dirt floor, or in apple crates,
and a few inches of soil is piled around each crown. Plants
can be held dormant with temperatures below 40 degrees.
Fertilizing
pH: Maintain a soil pH of 6.2 to 6.8.
New plantings: Before planting, apply 50 pounds N per acre,
0 to 150 pounds P2O5 per acre, and 0 to 200 pounds K2O per
acre based on soil test results and recommendations from
your state. Apply an additional 25 pounds P2O5 per acre
directly in furrows when setting crowns. Sidedress with 50
pounds N per acre after growth starts in the spring.
248
Midwest Veg Guide 2022
Leaf Spot of Rhubarb - Ascochyta
Fungus
Non-Pesticide
Fertilize in the fall for growth in the spring. Improves rapid,
strong plant growth and uniform establishment, and enhances
competitiveness. Remove older yellowed leaves or leaves
with lesions in the fall.
Phytophthora Blight of Multiple Crops -
Phytophthora Oomycete
Non-Pesticide
Use disease-free plants. Plant only on well-drained soil.
Established plantings: Each year before emergence, apply
50 pounds N per acre by broadcasting and incorporate by
lightly tilling. After harvests conclude, apply 30 pounds N
per acre. The total amount of N from fertilizer should be 80
pounds N per acre. No P2O5 is necessary if adequate
fertilization was achieved prior to planting. Every fourth year
apply up to 120 pounds K2O per acre if a soil test
recommends it.
Harvesting
Harvest no longer than 4 weeks, beginning with the third
season of growth. Harvest for about 8 to 10 weeks after the
third season. Do not remove more than two-thirds of the
developed stalks from any plant at one time.
Rhubarb is forced by wetting the soils around the crowns and
maintaining a temperature between 50° and 65° F. The plants
then produce many bright pink stalks for about one month
and are usually picked twice a week. After experiencing a
forcing process, crowns are generally too weak to produce
well again.
Rhubarb - Diseases
Reviewed by Dan Egel - Sept 2021
Recommended Controls
Midwest Vegetable Guide - 2022

Table of Contents for the Digital Edition of Midwest Vegetable Guide - 2022
