Eradicate Aphids safely with 50% Alcohol

TLDR:

Kill aphids on contact with 50% alcohol and a pump of biodegradable dish soap in a sprayer. Do NOT use stronger than 50%. 70% alcohol WILL burn your plant leaves. Use 98% alcohol and dilute 1:1 with water (49%). Or use 70% alcohol and dilute 2:1 with water (2 cup + 1 cup water = 47% alcohol). Add a pump of dish soap at the end, then shake and spray.

Full Post

We don’t use any pesticides or herbicides on our crops at Slow & Steady Farm. The only exception we make is early season when our peppers are still in their trays in the greenhouse, we need something to tackle the aphids. As a result, we need an effective spray that does not introduce harmful chemical residue in the soil or on the plants that can be consumed or disrupt our soil life.

We have experimented with Organically listed sprays such as Mineral Oil, or Neem Oil, which are relatively harmless, but they simply do not work well. Their mechanism of action is that of soap - a surfactant which increases the surface tension of the liquid, making it harder for an insect to escape a bubble of it, suffocating as a result. This can work, but it requires multiple applications per day for a couple weeks to ensure aphids are gone.

Alcohol kills aphids on contact within seconds.

In my experience, 50% alcohol kills aphids, wooly aphids, thrips, and other soft bodied insects in a few seconds. I add a pump of Planet brand certified bio-degradable dish soap to act as a surfactant to help increase the “stickiness” of the alcohol on the aphids.

Make sure to check the under-side of each leaf, holding the pepper sideways or upside down if you can. Also once your peppers have 6+ leaves, prune the bottom leaves that are touching each other or the soil to reduce the mobility of aphids from plant to plant.

Cost Analysis

Current Prices of 98% alcohol are about $5/pint, so 50% spray will run you $5/quart sprayer. We grow about 3,000 pepper plants in cells (about 100× 1020 trays from March to June), and we use about 1 pint a week, or $20/month, or $80/year or $0.03/pepper plant.

We consider this extremely cost effective. It also reduces labor involved with less effective sprays while maintaining our mission, introducing zero harmful chemical residue onto the plant or soil.

Cheers,

Blake