| Explore | We have learned that plants are often infested by parasites, organisms that latch onto leaves and take nutrients and water out from the plant. The host plant is often hurt by the parasites so farmers and gardeners have found remedies to reduce the spread of them. We have discovered in class the most popular remedies for parasite infestations are horticultural oil and an alcohol solution. These remedies work by poisoning the organism. We are interested in the questions of how effective these remedies are in reducing the insects and prolonging the life of the plant. |
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| Research Question | We are testing the question "Which is better at reducing brown soft scale insects: a store-bought remedy or a home remedy?" We came up with the question by using the four question strategy and listing out all the materials available to us and all the actions parasites do as well as thinking about how we would measure the results of each idea. The question fits what we know about the topic because we used researched information to select the two remedies. |
| Predictions | Our alternate hypothesis is that horticultural oil will be more effective than isopropyl alcohol in removing scale insects. We think this will happen because horticultural oil is made for this purpose. Our null hypothesis is that horticultural oil and isopropyl alcohol will have the same effect on the scale insects. |
| Experimental Design | 1) Wear safety goggles. 2) Shake the bottle of horticultural oil. 3) Measure 37.5 mL of water using a graduated cylinder and a pipette for more precision. 4) Pour the water into a small spray bottle. 5) Open the bottle of horticultural oil. 6) Measure 0.5 mL of horticultural oil using a pipette. 7) Pour the horticultural oil into the spray bottle. 8) Close the bottle of horticultural oil. 9) Put the lid back onto the spray bottle. 10) Tighten the nozzle to make sure nothing leaks. 11) Shake the solution very well for at least one minute or until it looks white and foamy. 12) Open the spray bottle. 13) Measure 12.5 mL of water using a graduated cylinder and a pipette for more precision. 14) Pour the water into the spray bottle. 15) Put the lid back onto the spray bottle. 16) Tighten the nozzle to make sure nothing leaks. 17) Shake the solution well again. 18) Loosen the nozzle to prepare for spraying the leaf. 19) Hold a piece of paper against the side of the leaf you are not spraying to cover it. 20) Spray the leaf with enough of the horticultural oil and water solution to cover it. This took our team 15 sprays. 21) Repeat steps 19 and 20 for the back side of the leaf. At the end of this step, both the front and back of the same side of the leaf should be sprayed. 22) Empty the spray bottle. 23) Rinse it out with water multiple times. 24) Get out 80% isopropyl alcohol. 25) Measure 43.75 mL of alcohol using a graduated cylinder and a pipette. 26) Pour the isopropyl alcohol into the rinsed spray bottle. 27) Measure 6.25 mL of water using a graduated cylinder and a pipette. 28) Pour the water into the spray bottle. 29) Put the lid back onto the spray bottle. 30) Tighten the nozzle to make sure nothing leaks. 31) Shake the solution well. This should make a 70% isopropyl alcohol solution. 32) Get cotton swabs. 33) Dip cotton swabs into the solution. 34) Use the cotton swabs to apply the solution and coat the entire half of the leaf, front and back. 35) Label four plastic, hexagonal trays with a number from 1 to 4. 36) Zero the balance. 37) Measure each tray and record the mass. 38) Wait for the horticultural oil to stop dripping off the leaf. 39) Place a wood plank on top of the rim of the pot. 40) Tape the leaf to the stem to make sure it stays in place. 41) Place two trays on top of the plank, one under each side of the leaf. 42) Make sure the other leaf is not too low to the table. 43) If it is, knot a few rubber bands together to form a longer rubber band. 44) Tie the rubber band around the part that connects the stem to the experimental leaf and the part that connects the stem of the plant to a higher leaf. 45) Place the trays underneath the leaf, one on each side. 46) Wait one week. 47) To collect data, measure the mass of each tray. 48) Repeat steps 1 through 47, excluding 35, 43, and 44, each week. Independent Variable: Type of remedy Dependent Variable: Amount of removal of brown soft scale insects Constants: Placement of plant, Plant (Dieffenbachia), Placement of plastic trays, Soil, Ratio of each of the remedies (1:100 for horticultural oil:water; 87.5:12.5 for alcohol:water), Sunlight |
| Conclusion | The data that this experiment produced was very different from what would be expected. The horticultural oil and horticultural oil control leaf both produced only 0.02 g of honeydew. However, the alcohol control leaf produced 0.01 grams of honeydew, and the alcohol leaf produced 0.04 grams. The control variance was understandable because we did not count the precise amount of scale insects on each leaf to begin with, but it was very unexpected that the leaf treated with alcohol (a so-called "home remedy") actually produced more honeydew than the control leaf. Also before the data showed a clear result, both of the leaves withered and turned brown. We were able to see that the leaf with alcohol had multiplied its amount of scale insects, and the leaf with the horticultural oil didn't show any increase in number of scale insects. Although both of the leaves died, we are able to conclude that the horticultural oil is a better remedy. |
| Investigation Theme | WOS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| School Name | High Technology High School |
| Session | Fall 2017 |
| About this Project | This team chose to design an investigation to determine the effectiveness of a commercial horticultural product vs. a DIY home remedy for ridding one of our large classroom plant specimens from an infestation of brown soft scale insects. Their strategy for keeping track of the amount of 'honeydew' product dropping from the infested and treated leaves was a most creative way of indirectly quantifying the amount of scale activity occurring on various parts of the plant. |