Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Many growers reuse stakes used in supporting crops such as tomatoes and peppers. Bacterial and fungal diseases have been shown to survive on wooden stakes and can be a source of new infections. Plant diseases survive on plant debris and soil on the surface of stakes and can also survive on the interior of stakes due to the porous nature of the wood. Therefore, where wooden stakes are reused, it is recommended that they be disinfected.
Before disinfecting, all crop debris and soil should be removed from stakes by brushing or washing or a combination. Dirt and debris can protect pathogens and de-activate disinfectants.
Disinfecting Options
- Soak stakes in a disinfectant solution for a minimum of 20 minutes (30 minutes preferred). Stakes should be completely submersed so solution surrounds each stake. Use weights to hold stakes under water. Options include:
- a) Chlorine bleach (5.25% sodium hypochlorite or higher) is commonly used as a disinfectant. Use bleach at a rate of 0.5% (=1 part bleach + 9 parts water). For more concentrated bleaches reduce rates accordingly. Use in a well-ventilated area. Soak stakes for 30 minutes. Chlorine bleach is effective; however, it is short-lived after mixing in water, with a half-life of only 2 hours, and it is inactivated by organic matter so additional bleach will need to be added or new solutions made up frequently. It is crucial to maintain the pH of the bleach solution within the 6.0 to 6.5 range, as effectiveness decreases at lower and higher pH levels.
- b) Quarternary ammonium disinfectants like Green-Shield is more stable than bleach after diluting with water. Use at a rate of 0.5 fluid ounce per of Green-Shield in 1 gallon water.
- c) Hydrogen dioxide, hydrogen peroxide and peroxyacetic acid products such as an OxiDate or SaniDate can also be used to disinfect stakes (some are organic certified). Check the labeled rate for the formulation you choose.
Tomato stakes soaking in a disinfecting solution.
5. Apply heat to stakes to kill pathogens present. This can be done with a commercial kiln, seed dryer, or pasteurizer. Heat should reach a minimum of 140°F for at least 30 minutes. Pathogens are eliminated from wooden stakes with exposure to ≥ 220°F for ≥ 15 minutes.
A steam pasteurizer that is used for soils can also be used to disinfect stakes.