PCC_MayJun_2019_e

Evaluation of Grafted Tomato Plants
for California Fresh Market Production Systems
By BRENNA AEGERTER | UCCE Farm Advisor for San Joaquin County
All photos courtesy of Brenna Aegerter
Why Graft?
Grafting involves joining a
fruit-producing shoot (called
the 'scion') of a desirable cultivar
onto the disease-resistant rootstock
of another cultivar. For example,
let’s say you normally grow the cultivar
'QualiT-47' for fruit production, but
that cultivar is susceptible to a soilborne
disease problem in your fields, then you
could graft the top part of a 'QualiT-47'
seedling onto the root-portion of a
more disease-resistant cultivar. In the
case of tomato rootstocks, the majority
of the cultivars are interspecific hybrids
Additional Environmental Stress Conditions that the product is useful for:
What is
Anti-Stress 550®?
When to apply
Anti-Stress 550®?
Frost & Freeze
• High Temperatures & Extreme Heat
• Drought Conditions
• Transplanting • Drying Winds
When is Anti-Stress 550®
most effective?
Beat the Heat & Care
for Your Crops with:
Anti-Stress
550 ®
A foliar spray that creates a
semi-permeable membrane
over the plant surface.
Optimal application period is
one to two weeks prior to the
threat of high heat.
*One application of Anti-Stress 550® will remain effective 30
to 45 days, dependent on the rate of plant growth,
application rate of product and weather conditions.
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Order from your PCA or local Ag Retailer / Crop Protection Supplier
between cultivated tomato (Solanum
lycopersicum) and wild tomato species
(most commonly Solanum habrochaites,
or less often S. peruvianum or S.
cheesmaniae). Solanum habrochaites is
known from other published research
to be tolerant of salinity, drought, cold
temperatures, and resistant to many
soilborne diseases and many of these
benefits have been demonstrated to be
conferred to the grafted plant when an
interspecific hybrid rootstock is used.
Most of us are familiar with grafting as
a standard practice for California fruit
and nut trees and grapevines, but it
has experienced only
limited commercial
The coating of Anti-Stress
becomes effective when the
product has dried on the plant.
The drying time of Anti-Stress is
the same as water in the same
weather conditions.
adoption among
annual crops in
California thus far.
Grafted tomato
transplants are
commonly utilized
in the commercial
greenhouse industry,
where tomatoes are
produced under
protected culture
and are generally
grown over a much
longer production
cycle, often a
10-month period.
There are greenhouse
producers in Southern
California, but it is
more common in
British Columbia,
Ontario, Mexico
and other US states
(Arizona and
others). In many
countries in Latin
America, Europe
and Asia, grafted
plants represent a
large percentage of
the tomato industry.
For example, in Spain, 50 to 70 million
grafted plants are grown annually for
greenhouse production systems. There
has also been some adoption of grafting
by high-tunnel tomato growers in the
eastern United States. In Southern
California, the nursery Plug Connection
is marketing grafted tomatoes to home
gardeners, dubbing them as a “Mighty
‘Mato”. This allows a home gardener to
grow an heirloom tomato variety, which
often has little or no disease resistance,
without worrying about rotation
or other soilborne disease control
measures.
Our goal was to evaluate the potential
for grafting standard tomato cultivars
onto rootstock cultivars that possess
resistance to soilborne diseases and
nematodes. Our primary objective
was to evaluate the yield performance
of grafted plants in replicated trials
in commercial fresh market (“mature
green”) production fields in the
northern San Joaquin Valley. Our team
consisted of myself, Scott Stoddard with
University of California Cooperative
Extension (UCCE) in Merced County,
and Michael Grieneisen and Minghua
Zhang in the Department of Land, Air
and Water Resources at the University
of California, Davis. This project
produced the first publicly-available
research results on grafted tomatoes for
California production systems.
How is it Done?
For each tray of grafted tomatoes to
be produced, two trays of seed are
sown; one tray of the rootstock seed
and another tray of the scion seed. At
approximately one month after sowing,
the young seedlings are grafted. Both
seedlings are cut at the hypocotyl, and
the scion shoot is spliced onto the
Continued on Page 20
18 Progressive Crop Consultant May/June 2019