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Lawn and garden diseases in Idaho

Blossom end rot

                                                              Blossom End Rot

















Blossom End Rot is a physiological disorder that is caused by a calcium imbalance within the plant.  It affects tomatoes where the tissue of the blossom end of the fruit (the area of the tomato that is opposite the stem of the plant, also known as the basil end) and as it breaks down, it turns dark brown to black and rots, thereby reducing the  overall productivity of the plant.  Many gardeners who have grown tomatoes in their garden are quite familiar with this problem.  Heavy losses may take place if preventive measures are not taken to rectify the problem. Blossom end rot can also be found in peppers, cucumbers, melons, and squash, however it's most commonly found in tomatoes.

Symptoms of blossom end rot may occur at any stage of development.  The disorder starts as a small, water-soaked spot which then enlarges and darkens rapidly as the tomato develops. The spot may enlarge until it covers as much as one-half of the entire tomato surface, or the spot may remain small and superficial. Large lesions soon dry out and become a flattened, black, and leathery in appearance and texture. Blossom end rot can occur in green as well as red tomatoes.

Calcium is required for the tomato to grow and calcium acts like a glue as it binds the cells together.  Tomatoes absorb calcium through our watering of plant; typically however, calcium is not fast to relocate.  Calcium deficiency will not spread from plant to plant or from tomato to tomato since this disorder is physiological in nature and the use of fungicides and insecticides are of no value as a means of control.

This disorder is dependent upon a number of environmental conditions, especially those that affect the supply of water and calcium in the development of tomatoes. The movement of calcium within the plant is dependent of active transpiration.  Certain things that may influence the uptake of water and calcium by the plant may have an effect on the severity of blossom end rot.  Generally speaking, calcium moves from the roots of the plant and into the leaves were it remains.  It does not move from the leaves and then into the tomato with the exception of Hi-Yield ‘Calcium Nitrate’ which is the only form of Ca that moves into the fruit.  We recommend using this form of calcium at the time of planting and again when little tomatoes start to form and finally two or three weeks later.

Calcium deficiency is especially prevalent when rapidly growing, succulent plants are exposed suddenly to a period of drought. When the roots fail to obtain sufficient water and calcium to rapidly developing tomatoes, the tomato may become rotted on their basal ends. Another common problem is cultivating too close to the plant as this may this harm the root system which effects the uptake of water and other minerals. Tomatoes planted in cold, heavy clay soils may develop a poor root system. Since they are unable to supply adequate amounts of water and nutrients to plants during times of stress, blossom end rot could result. Soils that contain excessive amounts of soluble salts may also predispose tomatoes to this disorder. The availability of calcium to plants decreases rapidly as total salts in the soil increase.

To sum this up, inconsistent watering practices, root damage, cold temperature or cold soil conditions, excessive heat, too much nitrogen, and/or too much salt in the soil are all situations that can lead to blossom end rot.

control  measures...

Control of blossom end rot is dependent upon maintaining adequate supplies of moisture and calcium to the developing tomatoes. Tomatoes should not be excessively hardened or too succulent when planted. Tomatoes should be planted in well drained, adequately aerated soils. Tomatoes planted early in cold soils are more likely to develop blossom end rot on the first set of fruits, with the severity of the disease often subsiding as the weather warms.  Planting tomatoes in warmer soils will help alleviate part of the problem. Irrigation must be sufficient to maintain a steady even growth rate to plants.

Mulching of the soil is helpful in maintaining adequate supplies of soil water in times of moisture stress. When cultivation is necessary, it should not be too close to plants or so deep that the feeder roots are injured. Shading plants can be helpful when hot, dry winds occur.  The use of fertilizer that is low in nitrogen, but high in phosphate are excellent fertilizers and Ferti-lome ‘Tomato and Vegetable Food’ will help alleviate problems related to blossom end rot. Another factor that will help with blossom end rot is Ferti-lome ‘Yield Booster’.  The foliage can be sprayed to help control this disorder; however foliar treatment is not a substitute for proper treatment of the soil.

other thoughts…

Many avid gardeners are aware that differences exist among different varieties of tomatoes in regards to the susceptibility to blossom end rot.  Once a tomato has blossom end rot, the problem cannot be reversed in that tomato.  Tomato’s that are infected with this disorder should be removed so the energy can be redirected to healthy tomatoes.  Tomatoes infected with blossom end rot can be eaten as long as no other problems are present, however we recommend discarding any tomatoes infected with blossom end rot.

Tomatoes perform best when the pH of the soil is between 5.8 and 6.5.  Tomatoes need about one to three inches of water each week and they perform best when they are watered deep several times each week rather than a light, but often watering schedule.  Many gardeners have found that indeterminate and semi-determinate tomatoes are less prone to this disorder since it’s somewhat easier to regulate calcium intake.

To improve fruit set, we recommend using Ferti-lome ‘Tomato & Pepper Set’.  Apply to the back of the blossom and to the adjacent stems.   Repeat this process every 10 to 14 days.  This product will not only increase the yield of the plant, but will also increase the ripening process.
























This problem often occurs in alkaline soils. There are several ways to treat chlorosis without involving a specialist. When a tree is as bad as you see in this picture, we recommend using EDDHA Iron Chelate 6.0% concentrate. We recommend this formula when the soil pH is 7.0 or greater. Homeowners often start seeing results within two to three weeks after applying. This product is a powder and it's important to follow directions when applying any water soluble product.

The second product is Medicap FE systemic Iron implants for trees. This requires you drill a 3/8-inch hole in a tree. The amount of product depends on the diameter of the trunk and the directions are clearly stated on the package. We recommend using Medicap FE systemic Iron Implants for chlorosis in an Autumn Blaze maple for example.

If you need further information on this or have any other gardening question, please give us a call at 208.917.4820 or stop by the nursery at 4291 S. Cloverdale Rd. in Boise.

Chlorosis in maple trees
Example of fairy ring in a lawn

Fairy Ring in Sod













Fairy ring can be found in lawns throughout Idaho.  Mushrooms are often a prelude to its presence.   This disease can exist in the soil for two or three years prior to recognizing its existence.   A gardener may recognize its presence when dark green circles of grass appear in the lawn.  You may also see mushrooms growing in areas where the sod has turned a dark green color.  Inside the circle, the grass will become light green and then turning dead brown!  As the fungus develops, the circle will continue to grow larger.   As the sod decomposes, it releases organic nitrogen into the soil, giving way to a healthy appearing, dark green sod.  The fungus will produce cotton-like webbing called mycelium. As the mycelium dies, it will become quite hard and restrict the intake of water into the soil.  This in turn will cause death to the sod within the circle.

Cause of problem:

There are several causes of fairy ring.  In our area, the most notable cause is overwatering.  Overwatering brings about decay to dead roots of plants and decaying thatch.  As the fungus starts to develop, it will survive on thatch, but ultimately it kills grass crowns.  Do not dig or attempt to remove damaged areas caused by fairy ring.  You will only help spread contamination of the soil.  If you should dig into the soil where fairy ring exists, be certain to clean the shovel thoroughly using a mixture of 30% bleach and 70% water.  Oil the shovel after cleaning since bleach can cause garden tools to rust.  Fairy ring has been known to briefly disappear for some time and then show up again. 

Controlling fairy ring:

Controlling Fairy Rings is very difficult.  Before anything else, reduce your watering schedule.  If you see mushrooms starting to grow in a semi-circle, immediately cut back on watering.  Now, assuming that fairy ring exists, We recommend  Ferti-lome ‘Consan 20’ and applying it once every 2 weeks throughout the season.  The label on the product recommends 1 tablespoon per gallon of water and one gallon of solution should cover approximately 40 square feet of surface area.  Since fairy ring is so difficult to control, we recommend applying this solution to the entire lawn.  A second recommendation really won’t help resolve fairy ring, but it will certainly make it less noticeable.  That recommendation is to apply Ferti-lome ‘Lawn Food plus Iron’.  As we said, it only makes the problem less apparent plus it provides an iron supplement  to the soil, an essential  element in our alkaline soils.  Other  options for  treating fairy ring include gypsum and penta-turf.  If you apply gypsum, do not dig it into the soil!  Apply to the surface and water it in.  Gypsum is slow to work and so is fairy ring.  It may take several  years to eradicate this disease.


Maintaining a healthy lawn is certainly the best defense when it comes to avoiding many diseases and insect problems in the lawn.

We're here to help:

The Home & Garden Store would like to thank you for visiting our website.  We have over 47 years of nursery/landscape experience right here in the Treasure Valley and can help you with all your gardening questions.  Our nursery/garden center has an Idaho Certified Nurseryman on staff to guide you in making the right decisions with plants, plant diseases, weed problems and other gardening questions.  Give us a call at 208.917.4820 or stop by our garden center at 4291 S. Cloverdale Rd. in Boise, Idaho.































Diseases in the leaves of aspen can reduce the aesthetic value of these trees.  Typically, leaf diseases on aspen are not going to kill the plant, but it certainly diminishes the value of the tree itself.  Should a tree lose leaves during the early summer months and the tree is otherwise healthy, it should reproduce new buds which in turn become leaves.  As with any tree, when a tree loses leaves too early in the late summer months, it also loses its ability to store nutrients. 

 Probably the most common leaf disease in our area is Marssonina leaf spot.  Marssonina leaf spot, also called Black Leaf Spot, is a common disease in quaking aspen and can often be found in some varieties of cottonwood.  This disease is most often recognizable by small, dark brown to black spots which appear on leaves affected by the disease.  At times there may be yellowing on the outer part of the leaf.  As late summer arrives, these spots tend to fuse together and form large dead patches on the leaves.  Leaf diseases intensify throughout the summer and progress from the base of the plant and proceed upwards until reaching the top of the tree.  Fall colors are sometimes less intense when infected with leaf diseases.  Marssonina leaf spot is typically most noticeable in July and August.  The disease has a tendency to spread rather quickly when given the right conditions and may travel great distances when the wind allows such.  The fungus survives the winter in the fallen leaves and other weed debris on the ground and as it warms up during the spring, it releases the spores and starts the cycle over again.

Being that quaking aspen have shallow roots and loves lots of moisture, it’s the ideal situation for developing Marssonina leaf spot disease.  If the tree doesn’t get enough water, the tree suffers, too much water and the tree develops Marssonina leaf spot.  Typically Marssonina leaf spot flourishes when the temperature is between 60 to 80° F.


There are several ways of controlling Marssonina leaf spot.  First, control the amount of moisture applied by fairly deep watering once every 7 to 10 days as this forces the roots a little deeper in the soil.  Second, NEVER water at night!  This is not the only fungus that will develop when you water at night.  Third, air circulation is critical.  It helps dry-out areas that might otherwise stay moist and induce fungus spores.  Fourth, place approximately 3-inches of mulch below the tree.  This helps preserve moisture around the root system while keeping leaves and other debris relativity dry.   Fifth, when you do develop Marssonina leaf spot or any other leaf fungus on Quaking Aspen, start treating with Natural Guard ‘Copper Soap Liquid Fungicide’ at the first sign of a fungus.  Follow the directions closely as copper fungicide must be applied on a regular basis to be effective.  Start treating as soon as you recognize that a problem exists.


The steps above is certainly a great line of defense for quaking aspen, but as a general rule for this plant as well as all other plants in the landscape, removal of leaves, fallen branches, dead foliage and other dead or decaying material should be removed from the site. 

While there are several other blights (Ink Spot, Leaf and Shoot Blight, Septoria Leaf Spot, and Leaf Rust) that may affect quacking aspen, we have found that Marssonina leaf spot to be the most prevalent fungus in our area.

Disease, Marssonina Blight on Aspen
Marssonina Blight
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