Vegetable Grafting—

a Pest Management Perspective

Sanjun Gu

State Vegetable Specialist Lincoln University in

Missouri

Outline Vegetable Grafting: some examples Vegetable Grafting: the Concept The Pest Management and Vegetable

Grafting Grafting Methods: the very brief New challenges in Vegetable Grafting The labor concerns Vegetable Grafting Research

Lisbon, Portugal 2010 --Increase vigor and yield

Ji’nan, China 2010 --The best watermelon

• Increased vigor •Enhanced cold tolerance •Improved yield and quality •Increased disease resistance

Photo: Dr. Wayne Fish --a Fusarium infected watermelon field

China, June 2010

Overwinter cucumber • Cold resistance • Disease resistance • Much enhanced vigor •High yield

Overwinter eggplants • Cold resistance • Disease resistance • Much enhanced vigor •High yield •Enhanced color

In Japan and South Korea

Watermelon: 91% Cucumber: 79% Eggplant: 57% Tomato: 41% Greenhouse production of the above: >90%

North/Central America About 40 millions of grafted hydroponic

tomatoes (Ontario or British Columbia) Less than 100k grafted watermelons in open

fields. Mexico had over 1250 acres of grafted

tomatoes to overcome Fusarium. Mexico also has many grafted watermelons

for Fusarium resistance (Abott&Cobb) Many farmers are interested in tomato

grafting, especially with heirlooms because of the disease resistance

What is Grafting?

Scion

Graft Union Rootstock

Advantages: Pest management The phase out of Methyl Bromide Fumigation made the

control of soil-borne disease difficult

Resistance to some soil-borne diseases Fusarium wilt: melon, cucumber and tomato Bacterium wilt: tomato, eggplant. Verticillium wilt: tomato.

Resistance to root-knot nematodes: cucumber, melon, watermelon, tomato, eggplant.

Grafting can transfer resistance against the carmine spider mite from Lagenaria rootstocks to Cucurbita scions.

Some rootstocks can render grafted plants resistant to some viruses.

•Fusarium wilt: cucumber, melon, watermelon, tomato •Bacterial wilt: tomato, eggplant •Verticillium wilt: tomato, eggplant •Phytophthora blight: pepper •Nematode: tomato, melon

From Sally Miller, Ohio State Univ.

Tomato Spotted Wilt

TSW incidence (%) Non-grafted: 79.8 a Self-grafted: 79.3 a Grafted: 59.5 b Rootstock: 1.3 c

Riley et. al. 2011

Zhao, 2010. Personal communication

Root Nematodes

Ungrafted: 4.6 Self-Grafted: 4.4 Grafted: 0-0.8

Galls rated at a 0-5 scale. Zhao, 2010 personal communication

Disease Resistance of Grafted Vegetables Disease resistance /tolerance in grafted

plants: not well understood.

Tomato

(Rivard and Louws, 2008)

Tomato Rootstocks

Cucurbit Rootstocks

Rootstocks for Watermelon Grafting

Rootstocks for Cucumbers

Vigorous root systems of the rootstocks Increased uptake of water and minerals in

grafted plants Lower ion concentration in xylem sap from

grafted plants due to the increased absorption of water and possible dilution effect

Rootstocks affect uptake and translocation of N, P, Mg, Fe, and Ca.

Water and Nutrient Uptake

Vigor of “Grafted Hybrid”

Modification of endogenous plant hormone (e.g., cytokinins) status by rootstocks

Gene expressions in the scion associated with various aspects of plant metabolism can be affected by rootstocks (Zhang et al., 2008).

long-distance translocation of RNA (Kudo and Harada, 2007) and protein (Gόmez et al., 2005) through phloem in grafted plants

Rootstock-scion interaction

Select scions and rootstocks

Schedule the best time for grafting

Conduct grafting

Plant seeds

The healing process

Acclimate the healed grafts

Plant grafted transplants

Grafting Flow Chart and Methods

Tubing Grafting method

Some Pics. from NC State University website (The Peet group)

Insertion method

Cucumber: tongue approach method

Rootstock: Cucurbita ficifolia

Scion

Rootstock Scion

Cleft Method

From Xin Zhao

Management of Grafted (Tomato) plants

Graft union should be at least 1 inch above the ground when planting

Keep removing suckers or lateral shoots arising below the graft union

Keep one or two leaders depending on the rootstock varieties used

Other management the same as that for normal tomato plants

Suckers should be REMOVED

Cost Analysis

WATERMELON Non-grafted (seedless) watermelon - $0.28 Grafted (seedless) Watermelon - $0.75

$704 more per acre (1,500 plants) 12.6% return on investment when

Fusarium wilt is problematic

Adapted from Dr. Wayne Fish

Grafted and nongrafted transplant production costs were $0.59 and $0.13 in NC, and $1.25 and $0.51 in PA, respectively.

Direct costs associated with grafting (e.g., grafting labor, clips, chamber, etc.) accounted for 37% to 38% of the added cost of grafting.

Grafting labor was 11.1% to 14.4% of the cost of grafted transplant production.

Seed costs represented 52% and 33% of the added cost of grafting at the two sites.

Indirect costs (e.g., soil, trays, and heating) accounted for 10% and 30% of the added cost of grafting.

Rivard et. al. 2010

Tomato Plants

North Carolina State Univ.: tomato Ohio State Univ.: tomato, watermelon Univ. of Arizona: tomato and melon Clemson Univ.: watermelon Texas A&M: melon Univ. of Florida: watermelon and tomato USDA : watermelon and Solanaceous crops

Research Examples in the U.S.

Some info from Dr. Zhao

Research at LU

Grafting Compatibility with Heirloom Tomatoes

Grafted watermelons Training and Nutrients management of

Grafted Tomatoes

Grafting greenhouse type cucumbers

Questions?

Sanjun Gu State Horticulture Specialist Cooperative Extension and

Research Program Lincoln University of Missouri 820 Chestnut Street Jefferson City, MO 65102-0029 Phone: 573-681-5524 Fax: 573-681-5313 E-mail: sanjun.gu@lincolnu.edu