Part Three: Plant Diseases and Pests

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by Don Herzog

Originally Presented at the 17th National Garden Railway Convention in Seattle, Washington, 2001

Part One: Soil and Water
Part Two: Climates and Micro-Climates
Part Three: Plant Diseases and Pests

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In the thrid and final portion of this article, we will look at some of the ebemies of plant life on the garden railroad line. Diseases are micro-organisms that make plants sick and may kill them. Pests are alrger organisms, from the size of a tiny insect to the size of a full-grown deer, that want to feed upon your railroad garden plants.

People who are new to miniature gardening often have concerns about how well such slow-growing and miniscule plants can be expected o survive outdoors. The truth is that many hardy plants come in small-leafed or dwarf forms and keeping them healthy is more a matter of making sure that have the right soil and water conditions than it is a matter of protecting them from diseases and pests. Still, it does help to understand the most common enemies of our minitature plants,m so here is a quick overview of what to look out for.


The diseases that our miniature plants get are usually varieties of fungus that cause root and/or stem rots.

Botrytus is a common white mold on the leaves. Other fungus appear by turning the leaves black, red and or yellow in solids or various patterns. All garden fungus initiate in wet weather when the temperature is between 50 and 55 degrees F. That is why we see more problems in warm wet weather in the Spring.

The way to help prevent fungus is to give all your plants a dormant spray in the winter and again just before new growth appears in the spring. I use a combination of copper and dormant oil for that purpose. I also spray my Japanese maples in September and March with Phyton 27. If your soil is heavy, add decomposed granite, rock, or river sand to help improve drainage.


The most common pests found on the plants we use are aphis, thrips, mites, and scales. All suck the juices from plants and may eventually kill them. Because garden railroad plants are miniatures and have less juices to suck than normal-size plants, they are especially vulnerable to predation by sucking insects.

Mites usually appear in hot weather and are very tiny. The others are easy to see. If you find the leaves on your plants looking off color or weird and can't see anything on them, then get a piece of white paper and place it below the leaves or needles. Then give the branch a vigorous shake. This is the only way to see the red spider mites crawling around. The best way to prevent these mite eggs from hatching on your plants is to use a dormant oil spray in the winter.


Your dormant sprays of fungicide and insecticide can be combined and applied at the same time. If the insecticide directions say to use a teaspoon per gallon of water and the fungicide directions say to use a tablespoon per gallon of water put both items in the same 1 gallon of water. Generally fungicides and insecticides can be applied together anytime during the year.

Be sure to consult your local nursery for the product you need, follow directions to the letter and store your insecticides and fungicides in their original bottles in a safe place away from children. Repeat the application in 7-10 days for best results. An infestation of mites may take 3 applications to eventually do in the last one.

For worms, spray with Bacillus thuringiensis, commonly known in the nursery trade as BT. Although this is technically an insecticide -- it kills insects -- it is not a chemical insecticide and is approved by organic gardeners.

About the Author:

Don Herzog has owned and operated Miniature Plant Kingdom in Sebastopol for more than 50 years, specializing in miniature and dwarf flowers, shrubs, groundcovers, and trees. During that time, he purchased one of the first LGB brand large-scale trains to arrive in the United States and helped start the LGB Club, the REGRS club, and the first Garden Railroad Convention. In 1972, he built a 30 by 40 foot garden railway layout and in 1992, he built a second garden railyway layout 55 by 85 foot in size. After retiring from the nursery business, he tore out those layouts and commenced work on his final layout of 1/4 acre.