Use of Mineral for Pest Management in Organic Gardening

1

Mineral

Insecticides developed from elemental (mineral) sources mined from the  earth are classified as natural products and often cost  less than other processed or harvested insecticides. The toxicity of mineral-based insecticides depends on  the  chemical properties of the  mined ele- ments. Some  mineral insecticides such as sulfur are regis- tered for organic use and have relatively low toxic effects on  people and nontarget organisms. In contrast, lead arsenate is a natural mineral product that was cancelled as a pesticide in 1988  due  to its toxicity and persistence in the  environment.

Diatomaceous Earth

Diatomaceous earth is a fine particle  dust comprised of fossilized diatoms that is effective against slugs and soil-dwelling insects. Diatoms are small, usually single-celled phytoplankton commonly found in aquatic or moist environments. Diatoms are encased in- side a cell wall made of silica,  the  same  compound used  to make glass. Diatomaceous earth works  as a fine abrasive that disrupts the  exoskeleton cuticle of a slug or insect and causes  it to desiccate (dry out).

Insecticides developed from elemental (mineral) sources mined from the  earth are classified as natural products and often cost  less than other processed or harvested insecticides.

Use diatomaceous earth only in landscape areas  that do not contain edible plants (e.g., ornamental gardens) ;To create an effective barrier for slugs,  apply diatomaceous earth in a 3-inch wide,1-inch thick band around the  habitats that slugs use. Repeat applications after  periods of rain. Note, however, that diatomaceous earth can  also be toxic to beneficial insects such as predatory ground beetles and is highly toxic to bees if applied to blooms.

Elemental Sulfur

Elemental sulfur is a finely ground powder that can  be applied either as a dust or a spray. This mineral is one  of the  oldest pesticides known, and reported pest  resistance is rare.  Sulfur  acts as a metabolic disruptor (interferes with a chemical reaction, digestion, or the  transport of substances into or between cells) to in- sects such as aphids, thrips, and spider mites. Most  sulfur formulations have low toxicity to people but  can  be an eye and skin  irritant. Sulfur  is highly toxic to fish, so it is important to keep  it away  from water (ExToxNet n.d.).

Do not use sulfur on  a crop  just  before harvest if you plan to preserve it; sulfur can  produce off-flavors in canned products, and sulfur dioxide can  form, which may  cause  containers to explode. In addition, sulfur is phytotoxic to most crops if applied two  weeks  before or after  the  application of a horticultural oil.

Iron Phosphate

Iron phosphate is very effective at managing slugs and snails when combined with bait. Baited  iron phosphate usually comes in pellet form. Scatter the  product around the  crop  in need of protection and areas  where slugs seek refuge, such as garden bed  borders and rocks.  Liquid formulations are also available. Follow  label  suggestions for subsequent applications.

Insecticidal soaps  are very effec- tive  for managing soft-bodied insects like aphids, scales, whitefly, mealybugs, thrips, and spider mites.

Slugs that feed on  iron phosphate will stop  eating, usu- ally seek a hiding place, and then die of starvation. Iron phosphate is considered relatively nontoxic and does not affect  insects, birds, or mammals when applied in the recommended amount. Avoid  over-application, as there is some evidence that iron phosphate baits  can negatively affect  earthworms (Edwards et al. 2009). Because  iron phosphate is nontoxic only in the  labeled ap- plication amounts, be sure  to store  it in a safe place  away from pets  and children. Most  brands of iron phosphate are approved for organic production by the  National Organic Program.

Kaolin

Kaolin is a fine  clay that is sprayed on  plant foliage or fruit  to deter feeding and egg laying of insect pests  such as apple maggot, codling moth, and leafhop- pers.  It can  also have some repellant properties that cause  irritation to insects upon contact (Stanley 1998).

The effectiveness only lasts as long as the  clay film cov- ers the  fruit  or foliage to mask  its chemical, visual, and tactile cues.  Reapplication is necessary if rain  washes the  product off. Kaolin’s  toxicity to pests  is additionally dependent on  the  insect being on  the  fruit  or foliage during the  entire time of pest  susceptibility. You will need to monitor insect activity to be sure  that plants are protected during the  required times. Kaolin is an  organi- cally-approved material.

READ:  Organic livestock farming: benefits, principles, challenges

Soap

Natural soaps  are derived from plants (coconut, olive, palm, cotton) or animal fat (whale oil, fish oil, or lard) and have been used  since  the  1700s to control certain soft-bodied insects such as aphids (Olkowski et al. 1993). Soaps  are fatty acids  that can  degrade or dissolve the protective layers  of the  insect cuticle, causing the  insect to desiccate. Insecticidal soaps  are considered nontoxic to humans and many beneficial insects, but  selectively kill certain pest  insects. Some  soaps  are approved for use in organic agriculture.

Insecticidal Soaps

Insecticidal soaps  are very effec- tive  for managing soft-bodied insects like aphids, scales, whitefly, mealybugs, thrips, and spider mites. The soap must contact the  insect’s outer skeleton to be effective. Leaf-feeding insects are often found on  the  undersides of leaves, so be sure  to fully  cover  plant foliage. Results from the  application of soap  are usually seen  in 1–3 days. Multiple applications are often needed to be effective. Insecticidal soaps  are usually diluted with water before applying.

Do not use household soaps  as insecticides. Household soaps  vary  tremendously in composition, purity, and effectiveness, and thus have the  potential to harm crops.

For example, household soaps  can  be phytotoxic to some plants, resulting in leaf burn. Only use soaps  that are specifically registered and sold  for use as insecticides. Be sure  to read  the product label  for known phytotoxic effects  and always test  the  product on  a small portion of the  plant to see if leaf burn occurs. Leaf burn symptoms usually develop within two  days.

Admin

One thought on “Use of Mineral for Pest Management in Organic Gardening

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Next Post

Spinosad as Organic Pesticide

Tue May 21 , 2019
Some microbes can be fermented to produce an insecticide such as abermectins, a fermented product of Streptomyces avermitilis (Dybas 1989) used in baits for household insect pests. The best known home gardening product of this type is spinosad. Metabolites of Saccharopolyspora spinosa, a soil-inhabiting bacteria that is fermented, are the […]

Recent Post