United States Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine

Administrative action to add new heat treatment for plant 

pathogenic bacteria and fungi on dried plant parts including 

wood and articles made with wood

Treatment Evaluation Document

Date: December 6, 2012

Treatments, Pests, Commodities and Countries

New Treatment/ 

Revision/Deletion 

Treatment 

Type

Target Pests Commodity Applicable Country(ies) 

of origin

New Treatment Heat Plant pathogenic

bacteria and 

fungi

Dried plant parts

including wood and 

articles made with wood

All

Objective: To provide a heat treatment for plant pathogenic bacteria and fungi on dried 

plant parts including wood. Currently for lack of a treatment, dried plant parts, including 

wood and articles made with wood, infested with plant pathogenic bacteria and fungi are 

destroyed or sent back to country of origin. 

Overview: Dried plant parts, including wood and articles made with wood, are allowed

entry into the United States from many countries with an import permit and appropriate 

inspection. If a quarantine pest is found, the appropriate treatment must be conducted or 

the shipment will be destroyed or returned to the country of origin. Wood or articles 

made with wood are subject to some additional requirements as described in regulations 

7CFR319.40. Currently, except for certain T303 treatments used as dry heat (at 82.2 C or 

above for 2 hours) or moist heat (at 121 C or above for 15-20 min) specifically for 

articles made from rice straw, there are no broad spectrum heat treatments for plant 

pathogenic bacteria and fungi on dried plant parts. Dried plant parts, including wood and 

articles made with wood, infested with plant pathogenic bacteria and fungi are currently 

destroyed or sent back to country of origin. The PPQ Plant Inspection Station (PIS) at 

Linden, NJ has been requesting availability of treatments for plant pathogenic bacteria 

and fungi on a regular basis. There are treatment facilities in Linden, NJ that can perform 
2

the suggested heat treatment. This treatment was requested from PPQ in response to the 

interest expressed by importers of dried plant materials. 

Evaluation: APHIS’ Treatment Quality Assurance Unit evaluated the published data 

(Agrios, 2005, Pullman et al., 1981) and has recommended using heat treatment for plant 

pathogenic bacteria and fungi on dried plant parts including wood and articles made wirh 

wood. According to G. N. Agrios (2005), all plant pathogenic bacteria and fungi are 

killed at 80 C for 30 minutes. The exposure time for the moist heat treatment schedule 

given below has been increased to account for variations in handling the treatment. The 

dry heat exposure time has been further increased over moist heat since dry heat is known 

to take longer to kill bacteria and fungi than the moist heat, especially when used in large 

scale applications (Agrios, 2005, Pullman et al., 1981).

Addition of heat treatments for plant pathogenic bacteria and fungi on dried plant 

parts, wood and articles made with wood.

In order to facilitate safe trade of dried plant parts, including wood and articles made 

with wood, we are proposing the following treatment schedules to heat treat dried 

plant materials infested with plant pathogenic bacteria and fungi:

T500 series - Dried plant parts including and articles made with wood infested with 

plant pathogenic bacteria or fungi

Pest: Plant pathogenic bacteria and fungi

Treatment: T5XX: Moist heat at 80 C or 176 F for 1 hour

Treatment: T5XY: Dry heat at 80 C or 176 F for 2 hours

Treatment time does not start until the entire commodity has reached treatment 

temperature as measured at different locations. Possible heat damage to the commodity

must be determined before treatment. The commodity must not come in contact with 

heating elements or open flame. Treatment facility must be certified by APHIS and have 

a Compliance Agreement with PPQ.

Decision: Add the new heat treatments as explained above to the PPQ Treatment Manual 

for plant pathogenic bacteria and fungi on dried plant parts including wood and articles 

made with wood.

Originators:

Josie Cooley, Team Leader/Writer – Regulations, Permits and Manuals – Manuals 

Unit. 

Dean Komm, PPQ-CPHST-TQAU, Treatment Specialist

References:
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Agrios, G.N. 2005. Plant Pathology 5th edition. Elsevier Academic Press. Page 310. 

ISBN 0-12-044565-4 

Pullman, G.S., J.E. DeVay and R. H. Garber. 1981. Soil Solarization and Thermal Death: 

A Logarithmic Relationship Between Time and Temperature for Four Soilborne Plant 

Pathogens. Phytopathology 71:959-964.