Nematode extermination in place using heat blankets

• US 20060242900A1
• Filed: 12/20/2005
• Published: 11/02/2006
• Est. Priority Date: 01/05/2005
• Status: Active Grant

• Current Assignee: Reginald B. Lovelace
• Original Assignee: Reginald B. Lovelace
• Inventors: Lovelace, Reginald B.
• Granted Patent: US 7,469,500 B2
• Time in Patent Office: Days
• US Class Current: 47/58.1SC
• CPC Class Codes: A01M 17/00 Apparatus for the destruction of vermin in soil or in foodstuffs injecting fertilisers into the roots of trees A01G29/00
• CPC Class Codes: A01M 19/00 Apparatus for the destruction of noxious animals, other than insects, by hot water, steam, hot air, or electricity electric traps A01M23/38

Abstract

A system and method for nematode extermination in lawns using an array of insulated heat blankets (2) placed on the lawn, and energized in a controlled sequence to raise the soil temperature to an effective degree and depth to exterminate nematodes. An electric current controller such as a programmable logic controller (PLC) activates a first subset of the blankets (2) until they reach an upper setpoint temperature, then maintains the blanket temperature within a desired range with reduced current while activating additional blankets. The heat penetrates the soil over a period of about 20 to 50 hours to raise the temperature to at least about 52° C. (125° F.) at a sufficient depth such as at least 12 cm (4.7 inches) to kill at least most nematodes.

Claims

1. A method for nematode extermination in soil comprising:

placing a heat blanket on a surface area of soil;

placing thermal insulation over the heat blanket; and

energizing the heat blanket to achieve a first temperature range for a first period of time in the heat blanket in order to obtain a second temperature at a given soil depth for a second period of time that is effective for killing at least most nematodes in the soil under the blanket.

2. A nematode extermination method according to claim 1, further comprising:

placing a heat sensor on or under the blanket; and

wherein the energizing step comprises energizing the heat blanket to achieve the first temperature range between approximately 150°

C. (300°

F.) and 200°

C. (392°

F.) for approximately 20 to 50 hours to achieve a second temperature of at least 52°

C. (125°

F.) at a soil depth of at least 12 cm (4.7 inches).

3. A method for nematode extermination in soil comprising:

placing an array of heat blankets on a surface area of soil;

defining an electric load amount per heat blanket;

placing a heat sensor on or under each heat blanket;

providing an electric power source with an available load capacity;

providing a power circuit to each heat blanket connected to the power source;

providing an electric current controller connected to each power circuit and to the heat sensor for controlling an amount of electric current flowing to each blanket;

defining a first subset of the array of heat blankets comprising at least one blanket, the subset comprising a total power load amount up to, but not exceeding, the available load capacity;

activating the first subset of heat blankets to reach a temperature range as detected by the heat sensor;

maintaining the temperature range in the active heat blankets with reduced current for a period of time effective to kill at least most nematodes in the soil under the array of heat blankets;

activating at least one additional of the heat blankets within the available load capacity while the maintaining step is in progress;

further maintaining each active blanket within the temperature range until each blanket has been maintained in the temperature range for the period of time; and

repeating the “

activating additional”

step and the “

further maintaining”

step until each of the blankets in the array of blankets has been maintained in the temperature range for the period of time.

4. A nematode extermination method according to claim 3, wherein the temperature range is between approximately 150°

C. (300°

F.) and 200°

C. (392°

F.), and the period of time is approximately 20 to 50 hours.

5. A system for nematode extermination in soil, comprising:

a plurality of electric heat blankets, each blanket comprising an upper surface, a lower surface, and a thermal insulating layer on the upper surface of the heat blanket;

an electric power circuit connected to each blanket for energizing the blanket;

a temperature sensor in, on, or below each blanket that measures the temperature of the blanket;

an electric current control device that receives the temperature of each blanket from the sensor and controls the power circuits to reach a desired temperature range in a first subset of the blankets up to a total available current load, then reduces the current provided to the first subset of the blankets to maintain the desired temperature range in the first subset of blankets while similarly controlling additional of the plurality of blankets until each of the plurality of blankets has been maintained within a desired temperature range for a desired period of time; and

the desired temperature range is chosen to achieve a nematode extermination temperature at a desired depth in a soil within the desired period of time that is sufficient to kill at least most nematodes in a soil on which the blanket is placed.

6. A system according to claim 5, further comprising a power source connected to the power circuits, and an electric current measuring meter connected to the power source and interfaced to the electric current control device for providing a total current load measurement as input to the current control device.

7. A system according to claim 5 wherein the current control device uses a pulse width modulation scheme to time-slice electric current into pulses on each electric power circuit to proportion the current as needed by each blanket to maintain the desired temperature range.

8. A system according to claim 5, wherein:

the electric current control device comprises a programmable logic controller (PLC) connected to an electric relay on each power circuit; and

the PLC closes and opens each relay according to an algorithm that processes input from the temperature sensor, and processes parameters stored in the PLC comprising representations of the total available current load, a known current load amount resulting from activation of one of the blankets, and at least one set-point for the desired temperature and the desired temperature range.

11. A system according to claim 8, wherein at least some of the parameters can be entered and changed manually on a data input device connected to the PLC.