United States Department of Agriculture

Animal and Plant Health Inspection Service

Plant Protection and Quarantine

Administrative actions to add to the Treatment Manual a new 

hot water treatment (T201-p-4) for plant material not tolerant 

to chemical fumigation and to remove a less efficacious 

treatment (T201-p-3)

Treatment Evaluation Document

Date: October 11, 2012

Treatments, Pests, Commodities and Countries

New Treatment/ 

Revision/Deletion 

Treatment Type Target Pests Commodity 

Applicable

Country(ies) of 

origin

New Treatment Hot Water Pest List1Plant 

Material not 

tolerant to 

fumigation

All

Objective: To provide supporting information and justification for the addition of a hot 

water treatment, T201-p-4, for plant material not tolerant to fumigation, to the 

phytosanitary treatments described in the PPQ Treatment Manual (TM), and to remove a 

less efficacious hot water treatment, T201-p-3, from the TM. These actions are to help 

continue the safe trade of plant material not tolerant to the chemical fumigation. 

Overview: Currently under special permit conditions (also known as Departmental 

Permit), Plant Protection and Quarantine’s Plant Germplasm Quarantine Program 

(PGQP) in Beltsville, Maryland, is authorized to import prohibited plant material 

including: sugarcane, rice, grasses, potatoes, sweet potatoes, pomes, prunus, small fruits, 

etc., as germplasm collections and/or to carry out research activities. The permit 

 

1

Insects- Aphidae, Thripidae, Formicidae, Coccidae, Pseudococcidae, Diaspididae, 

Pyralidae, Tortricidae, Syrphidae, Scarabaeidae, Cucurlionidae, Tenebrionidae

Snails- Ampullariidae, Planorbidae

Mites-Acaridae, Tarsonemidae, Tetranychidae, Tydeidae

 Nematodes – Pratylenchus (genus only)
2

conditions for sugarcane state that plant material “should be selected from apparently 

disease-free and pest-free sources” and a “mandatory hot water treatment of sugarcane 

stalks” will be carried out at the Plant Inspection Station (PIS) at Beltsville, MD. While 

the plant material selected may be free of visible pests, certain pathogens that are latent in 

nature may cause imperceptible symptoms and thus escape detection. Hot water 

treatment is therefore required to mitigate risks from such pests. 

The hot water treatment referred to in the Department Permit is T201-p-3, which requires 

hand removal of visible pests followed by exposing the plant material to 50° C (122° F) 

water for 20 minutes. Although the treatment currently is used to treat only the plant 

material imported by PGQP as part of the germplasm collection, the treatment is 

approved for all plant material intolerant to fumigation regardless of its intended use.

This treatment is consistent with FAO/IBPGR Technical Guide for the Safe Movement 

of Sugarcane Germplasm (Frison and Putter, 1993). However, working with imported 

plant material over the years, PGQP has found this hot water treatment is not effecacious 

for many pests of concern that may accompany consignments. For this reason, and to

accommodate likely temperature fluctuations, the PGQP has found that an alternate hot 

water treatment at 52° C (125.6° F) for 30 minutes is more effecacious against a wide 

range of pests accompanying the consignments (Jeffers, 2011, pers. comm.). 

Based on the pest interception records, and the fact that plant material imported over the 

years into the United States has apparently not always originated from disease- and pestfree sources, the PGQP recommends use of the 52° C (125.6° F)/30 minute treatment for 

all plant material not tolerant to fumigation. Per recommendation, handpicking of visible 

pests where appropriate may still be required prior to hot water treatment.

The Departmental Permit also makes reference to availability of other treatments such as 

T201-c-1, which is fumigation with methyl bromide gas. However, the fumigation has 

generally been found to greatly reduce the viability of the treated plant materials and 

therefore not practical in all cases (Maroon-Lango, 2010, pers. comm.).
3

Evaluation: At the recommendation of PGQP, CPHST’s treatment quality assurance 

unit (TQAU) evaluated the research and determined that hot water treatment at 52 °C 

(125.6° F), for 30 minutes was adequate to control a wide range of external feeding pests 

as described below (Jeffers, 2011, pers. comm.). TQAU has therefore recommended 

addition of the 52 °C (125.6° F)/ 30 minute hot water treatment to the PPQ Treatment 

Manual. When adopted the treatment would be listed as T201-p-4 in the TM with the 

following information. 

T201-p-4 (New): Plant material not tolerant to fumigation

Pests: Insects- Aphidae, Thripidae, Formicidae, Coccidae, Pseudococcidae, 

Diaspididae, Pyralidae, Tortricidae, Syrphidae, Scarabaeidae, 

Cucurlionidae, Tenebrionidae

 Snails- Ampullariidae, Planorbidae

 Mites-Acaridae, Tarsonemidae, Tetranychidae, Tydeidae

 Nematodes – Pratylenchus (genus only)

Treatment: T201-p-4 (New): Hot water treatment – Hot water at 52 °C (125.6° F), 

for 30 minutes

Where appropriate, handpicking of all visible pests before hot water treatment will still be 

required.

For reasons as stated above, TQAU has also recommended removal of the treatment 

T201-p-3 from the TM.
4

Decision: Recommend addition of T201-p-4 hot water treatment at 52 °C (125.6° F) for 

30 minutes to and removal of T201-p-3 hot water treatment at 44.4° C (112° F) for 20 

minutes from the PPQ Treatment Manual.

Originators:

Laura Jeffers. PPQ-CPHST-TQAU, Pest Exclusion Specialist

References Cited:

Frison, E.A. and C.A.J. Putter. 1993. FAO/IBPGR Technical Guidelines for the Safe 

Movement of Sugarcane Germplasm. Food and Agriculture Organization of the 

United Nations, International Board for Plant Genetic Resources, Rome. 45 pp.