Each month V.D. Kaviraj will answer questions about plants and plant problems. Kaviraj is one of the foremost pioneers of Agro-homeopathy and author of the book, Homeopathy for Farm and Garden.
Send your questions with sufficient detail and pictures when possible (JPG or GIF format) to firstname.lastname@example.org with the subject “Plant Doctor”.
Note: When I refer to treating plants with homeopathic remedies, this is the standard dosing procedure: Put 20 drops of a 6X potency in a litre of water. Succuss the bottle 50 times. Put this litre in the watering can, fill it up with 19 litres of tap water and stir. If the watering can is smaller, the amount of remedy put in must be proportionally smaller. Thus a 10 litre can needs only ½ litre and just 10 drops of the remedy. Apply the contents of the watering can to the roots of the plants to be treated.
Hello Dr. Kaviraj,
I have a small lemon tree in my yard that has not grown an inch since I bought it 4 years ago. It always had only 2 leaves. It may not like the soil. We live 5km from the sea and I think the place I am living was covered by sea water in ancient times.
What can I do to make it grow?
First of all, you may want to have a soil analysis done. If the soil was once under water – sea water at that – it may have a high salt-content. Depending how long ago – if over 50 years then you have little to worry, unless it is lower than sea-level. In that case, Natrum mur may do the trick in neutralising the effects of salt water. If on the other hand it is well above sea level, the best solution seems to me to give it a dose of Carbo veg. That should settle it nicely. Please keep us posted about the progress.
Since permethrin (main ingredient in tick killer for animals) comes
from the marigold, is there some way to make a salve, cream etc. from
this plant, so the animals are protected but safe from the poison.
Hi Mike, you can also make a wash with Calendula tincture, about 100 drops on a litre. Wash the dog with it on a regular basis and that should keep the ticks off. If you use a cream or salve, you will stick the hairs in the pelt together and they will lose their isolation property and possibly make your dig catch a severe cold.
Our evergreen tree seems to be losing needles. We’re in the N.E. part of the U.S. and the soil the tree is living in is somewhat acid. Do you have any thoughts o this?
Pine trees love acidic soils. They are pioneer plants on acidic soils and the pH will therefore have little to do with it. I suspect a borer under the bark or another parasite, good at hiding in cracks. After you inspect the tree – bring a magnifying glass because many pests are extremely small – you may find a pest and this can be combated with Thuja. Alternatively, it could be a fungus and then you look for spores or hyphen – small, extremely thin web-like threads that infest the places where the needles have gone. In that case, use Salicylic acid to combat it.
It pays to read this month’s article on fungal diseases (below), because it will enable you to identify many fungal diseases with greater ease.
Function of Fungi
Fungi may be beneficial or detrimental to plants, depending upon the type, and what they use as a food source. In general, fungi are composed of microscopic cells that usually grow as long threads called hyphae, pushing their way between soil particles, roots and rocks. Hyphae are usually only several thousandths of an inch thick. A single hypha can span in length of a few cells to many yards. A few fungi, such as yeast, are single cells.
Hyphae sometimes group into masses called mycelium or thick, cord-like “rhizomorphs” that look like roots. Fungal fruiting structures (mushrooms) are made of hyphal strands, spores, and some special structures like gills on which spores form. A single fungus can include many fruiting bodies scattered across an area as large as a baseball diamond.
Fungi perform important services related to water dynamics, nutrient cycling, and disease suppression. Along with bacteria, fungi are important as decomposers in the soil food web. They convert hard to digest organic material into forms that other organisms can use. Fungal hyphae physically bind soil particles together, creating stable aggregates that help increase water infiltration and soil water-holding capacity.
Soil fungi can be grouped into three general groups based on how they get their energy. Decomposersâ€”saprophytic fungiâ€”convert dead organic material into fungal biomass, carbon dioxide, and small molecules, such as organic acids. These fungi generally use complex substrates, such as the cellulose and lignin in wood, and are essential in decomposing the carbon ring structures in some pollutants. A few fungi are called “sugar fungi” because they break down the same substances as do many bacteria. Like bacteria, these fungi are important for immobilizing, or retaining, nutrients in the soil.
Mutualistsâ€”the mycorrhizal fungiâ€”colonize plant roots. In exchange for carbon from the plant, mycorrhizal fungi help make soluble phosphorus and bring soil nutrients (phosphorus, nitrogen, micronutrients, and perhaps water) to the plant. One major group of mycorrhizae, the ectomycorrhizae, grow on the surface layers of roots and are commonly associated with trees. The second major group of mycorrhizae are the endomycorrhizae, that grow within the root cells and are commonly associated with grasses, row crops, vegetables, and shrubs.
The third group of fungi, pathogens or parasites, cause reduced production or death when they colonize roots and other organisms. Root-pathogenic fungi cause major economic losses in agriculture each year.
Saprophytic fungi are commonly active around woody plant residue. Fungal hyphae have advantages over bacteria in some soil environments. Under dry conditions, fungi can bridge gaps between pockets of moisture with their tube-like hyphae, and continue to survive and grow. In arid rangeland systems, fungi pipe scarce water and nutrients to plants. Fungi are able to use nitrogen from the soil, allowing them to decompose surface residue, which is often low in nitrogen.
Soil fungi are aerobic organisms. Soil that becomes anaerobic for significant periods generally loses its fungal component. Anaerobic conditions often occur in waterlogged soil and in compacted soil.
Four separate assays that help determine the types of fungi in soil and their extent of colonization are included in the next section. They may be performed concurrently or at separate times.
Seeing Soil Fungi
Fungi participate in a wide variety of soil processes. Some are mycorrhizal, increasing the capacity of plant roots to absorb nutrients. Fungi also secrete chemical compounds that dissolve minerals, making nutrients available to other organisms. Basidiomycetes are also associated with the ability of a soil to suppress plant disease. Some actinomycetes produce compounds that act as antibiotics. Streptomycetes sp. was the original source of streptomycin. As a group, fungi also help bind together soil particles, creating the fluffy “tilth” that is very desirable for root growth.
We often think of fungi as the “mushrooms” that are visible above ground. These are only reproductive structures, analogous to apples. The actually body of a fungus is a mass of microscopic threadlike filaments called a mycelium. Each thread is called a hypha (pl. hyphae). The everyday functions of fungi, secreting enzymes and absorbing nutrients, are carried out by the hyphae. In some fungi, a segment of hypha may contain several nuclei, so a section of hypha is not quite the same as a cell. Forest soils from the PNW often contain hundreds or thousands of meters of hyphae!
In general, the more fungal hyphae found in a soil sample, the healthier the soil, and the more able to support plant life. Mycorrhizal fungi increase the capacity for plant roots to absorb nutrients, as they secrete chemical compounds that dissolve minerals, making nutrients available. Basidiomycetes are associated with the ability of a soil to suppress plant disease. Some actinomycetes produce compounds that act as antibiotics. As a group, fungi also bind together soil particles, creating fluffy “tilth” that is very desirable for root growth.
Types of Fungi Present in Soil
Wear a latex glove for this assay, so fungi from fingers don’t contaminate the sample. Place a thin slice of potato in a petri dish that has been lined with a moistened paper towel. Place a sample (a pinch) of site soil in the center of the potato slice, spreading it into a circle about 1 cm in diameter. Repeat this for 2 more potato slices, each in its own petri dish. Leave the petri dishes in a dark place, and do not disturb for 2-10 days. After that time, examine the potatoes for fungal growth. Four general appearances are listed below, along with the type of fungi most commonly associated with each:
Gray & fuzzy growth – disease-causing fungi
Solid white growth – beneficial fungi
Solid brown growth – mostly basidiomycetes
Crinkly appearance – actinomycetes
If a diverse fungal community is present in the soil, different types of fungi may be present on the three potato slices. More than one type may be present on a single slice. In an unhealthy soil, disease-causing fungi will predominate on the slices. These fungi cause the familiar symptoms of rots, blights, and damping-off (a disease in which seedlings shrivel up at the soil surface and die).
If basidiomycetes are the dominant form on the slices, the soil is likely to be very healthy. These fungi form the classic “mushroom” as a reproductive structure. They are primarily decomposers of wood.
Actinomycetes are really filamentous bacteria. They give soil its “earthy” smell. If they are present in great numbers, the soil may be considered less than healthy. Some actinomycetes can produce compounds that inhibit the growth of arbuscular mycorrhizal (AM) fungi, so a predominance of actinomycetes may reduce the growth and vigour of grasses and garden vegetables, which are colonized by AM fungi.
Such problems can be solved with a good layer of the right dung and/or some liming and the fungi become less dominant, since the soil acidity has been changed. Fungi are therefore a sign of the grade of acidity of the soil, coupled with the amount of organic matter present. If the soil is bare, one sees the gray and fuzzy growth, while in healthy soil the basidomycetes are predominant and solid white growth is often also seen, next to each other.
‘Fungi and bacteria can cause a wide variety of problems. Bacteria are minute plants, which can cause rotting, wilting, and the forming of galls.’ Bacteria do not fall under plant classification – this is simply nonsense. Bacteria are micro-organisms, which also live in our gut and the guts of all animals. Their function is digestion or decomposition and when there is enough organic matter available, they will not cause any problems in the garden. They are not even visible to the naked eye.
‘Fungi, which are usually visible to the naked eye, cause rust, spots, mildew, and damping-off. Both are generally encouraged by moisture, warmth, and humidity.
‘Control these problems with the proper fungicide or by removing and destroying diseased plants. Purchase disease-free or treated seeds and plants. Crop rotation, staking, mulching, and adequate soil drainage are also important.’
That is all they have to offer – purchase treated seed or use fungicides. We have the systemic option – treat the plant and solve the problem in the soil by adding humus, compost or manure. We do not advocate such measures because they are but a wild goose chase. Fungi are soil borne and their function is decomposition of plant litter, humus, manure or compost. If none of these are present the fungus will go for the living plant.
Hence we must make sure first that the fungus is kept busy – make nature work for you! Next we must use the appropriate remedy which will change the situation underground to the extent that the fungus no longer likes the plant and is checked in its further development; exactly what would happen in a natural setting, where other entities in the habitat cooperate with our crop to maintain an optimum balance.
Fusarium wilt – brassicaceae, Cucurbitaceae, Leguminosae, Solanaceae.
Fusarium wilt is a common problem amongst beans, peas, cabbage, sweet potatoes, tomatoes, and watermelon. The disease, which is caused by fungi, will at first cause the lower leaves to curl downwards. Latter, the leaves will yellow and the plant will become stunted. A cross section of the lower stem will reveal dark brown streaks running lengthwise.
Purchase wilt-resistant varieties of seeds and plants. Do not plant in a soil that has been infected by the disease. Crop rotation will naturally help.
Verticillium wilt – Solanaceae
Verticillium wilt is a fungus disease which affects tomatoes, potatoes, and eggplants. Initially the lower, older leaves yellow and droop. These lower leaves will fall off and the disease will spread to the rest of the plant. Often only the leaves at the tips of the plant remain. Of course this causes stunted growth of the plant and its fruit. In the case of tomatoes the fruit will remain small and undesirable.
Since this disease is soil-born, tomatoes, potatoes, and eggplants should not be planted where these same plants have been grown before. Remove any infected plants from the garden immediately and destroy them.
‘Fungi and bacteria can cause a wide variety of problems. Bacteria are minute plants, which can cause rotting, wilting, and the forming of galls.’ Bacteria do not fall under plant classification – this is simply nonsense. Bacteria are micro-organisms, which also live in our gut and the guts of all animals. Their function is digestion or decomposition and when there is enough organic matter available, they will not cause any problems in the garden.
‘Fungi, which are usually visible to the naked eye, cause rust, spots, mildew, and damping-off. Both are generally encouraged by moisture, warmth, and humidity.
‘Control these problems with the proper fungicide or by removing and destroying diseased plants. Purchase disease-free or treated seeds and plants. Crop rotation, staking, mulching, and adequate soil drainage are also important.
This list provides an international account of crop diseases. It begins with the causes of diseases. In addition to carrots and celery, diseases of parsnip, cumin, coriander, parsley, caraway, and cilantro are included.
The list describes infectious diseases caused by fungi, bacteria, nematodes, viruses, and phytoplasmas as well as noninfectious disorders caused by air pollution, allelopathy, mineral deficiencies and toxicities, pesticide-related injury, and many others. The description of each disease includes symptoms, causal organism or agent, disease cycle and epidemiology, control, and selected references. Control measures stress homoeopathic principles and cultural practices that apply to most growing areas.
This approach is ideal for plant pathologists, crop production specialists, growers, diagnostic clinicians, students, regulatory agents, crop consultants, educators, researchers, extension personnel, and others interested in the diagnosis or management of diseases of crops throughout the world.
Internal black spot
This disease is one of many affecting potatoes. Prevent this problem by not overfertilizing the plant with nitrogen.
This fungus-causing disease affects potatoes, peppers, eggplants, and particularly tomatoes. It first appears as dark brown or black spots with rings similar to a “target” design. The disease first strikes the lower leaves and then may spread to the upper leaves. The infected leaves will wilt, yellow, and often die. Sometimes the problem will spread to the stems and fruit. We recommend Aconite and/or Silicea to control this fungus.
Crop rotation is important, as the disease can remain in the ground for about three years. Use seed that has been hot water treated. Treat your own seed with Thiram. Early blight is encouraged by moisture, warmth, and humidity; so provide adequate drainage and ventilation. Control outbreaks of the disease with a fungicide, such as chlorothalonil or Maneb. An organic approach would be to simply remove and destroy infected plants to prevent spread of the disease. Also, avoid working the garden after watering to reduce the chance of spreading diseases. Water early in the morning, to give the plants time to dry off.
Late blight is a fungus causing diseases which affects potatoes and tomatoes. It most often occurs in long wet periods of weather. The disease first manifests itself as dark green or black water-soaked spots. Occasionally the affected leaves will have a white powdery mildew on the underside of the leaves. Leaves will droop and appear as though they have been scalded or frost bitten. Fruit will develop rot and decay. Use of the proper fungicide is helpful, but infected plants are usually removed to prevent spread of the disease. Preplan by selecting certified, disease-free seed and plants.
Like the preceding, it girdles stems at ground level when the plants are young. On older plants, cream-coloured dots enlarge to dark brown or black-zoned patches. Spraying with Aconite or Belladonna at the beginning of the growing season will control it. It occurs largely on outdoor snaps.
This is a disease which affects carrots. Crop rotation can be helpful to inhibit spread of the disease. Also, purchasing hot-water treated seeds is recommended.
Here is another “classic” disease which causes tremendous damage, especially to azaleas. Several plant pathologists worked on it, but it was not until Dr. Cynthia Westcott discovered, in 1945, that Dithane-D-14 was a specific control, that it could be kept in check. Azalea petal blight is mentioned here because the resting stage survives on the soil under the plants. Here it can be killed by calcium cyanamide. Unfortunately, this is of little value except in protected, isolated gardens where a single plant is infected. The spores float for miles to infect blossoms, which turn a watery brown.
This disease is the bane of many plants, including some types of lilies; it often kills L. candidum (Madonna lily) bulbs in the soil. It is, however, spread above ground and comes within the scope of this soil disease discussion only because it moves down the stem and under the soil. Other lilies are less drastically affected. Spots are at first small purplish or brownish, fading to yellow. Leaf may finally collapse. Spraying with Bordeaux mixture is the old-time remedy. When tulips are infected with Botrytis Blight (tulip fire), small yellow or brown dots enlarge and cover the entire plant, flower and all. Leaves and petals look as though scorched by fire. Infected bulbs may carry the disease. Imported Dutch bulbs are reasonably clean.
Leaf spot diseases are caused by fungi and bacteria. Infected leaves have spots which appear as dead tissue. These spots can be yellow-green, tan, or black. The problem is particularly noticed on plants whose leaves are to be consumed, such as turnip greens. The spots will sometimes first appear as dark green water soaked spots. The spots are generally 1/16 to 1 inch in diameter. Remove infected leaves promptly and follow up with an application of fungicide, such as Maneb or chlorothalonil. Also, crop rotation can be a good preventative measure.
Lettuce rot is caused by the lower leaves coming in contact with the soil. The rotting of the lower leaves will often spread to the rest of the plant.
Prevent this problem by applying a layer of sand around the base of the plant. This will improve drainage and keep the leaves from laying on the moist soil which encourages rotting.
Mildew is a fungus. The term mildew includes powdery mildews, which are true mildews, and downy mildews, which are false mildews. True mildews lie on the surface of the affected plant and feeds on the plant through tiny suckers. False mildews are living on the internal fibers of a plant and appear on the surface of the plant. Mildews come in a variety of colours, but true mildews are generally white in colour and occasionally black.
Prevent mildew by planting in a sunny, well-drained area. Plenty of air flow and ventilation will also discourage the growth of mildew.
Downy mildew is not actually a true mildew at all. Unlike true mildews which grow on the surface of leaves, downy mildews originate from within the tissues of the affected plants. Downy mildew appears as yellow, white, gray, or purplish patches on mainly the underside of leaves. The patches are actually the spores of the fungi affecting the plant. Downy mildew can also be seen on stems and fruit. Lima beans, for instance, will develop a white downy mildew on the pods and eventually turn into black patches of mildew. This is a particular problem during long wet periods. Affected leaves will often not develop properly and fall off the plant.
Infected plants and diseased leaves which fall off the plant should be removed and destroyed. Crop rotation and adequate water drainage are also helpful. One control of the downy mildew is the chemical zineb. An organic solution to the problem is dusting with lime, flour, or sulphur.