Beware of blossom end rot

Posted 5/20/18

This is an article topic that I normally reserve for later in the growing season, especially for home garden crops such as tomatoes, peppers, watermelons and a few others; however, weather conditions …

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Beware of blossom end rot


This is an article topic that I normally reserve for later in the growing season, especially for home garden crops such as tomatoes, peppers, watermelons and a few others; however, weather conditions seem to be shaping up for some possible problems later on in the home garden.  

Since we are still fairly early in the planting season, hopefully with a little bit of planning and some preparation we can avoid some of those problems later on during the summer time when we expect to harvest those high quality home grown fruits and vegetables.

Dry conditions like we have experienced once the early spring rains ended usually means less disease problems in the garden. Most diseases are caused by fungi during humid wet weather. 

One thing that can get homeowners in trouble with fungal diseases even in dry summers is excessive overhead watering at the wrong time of the day. 

If possible, limit overhead watering to the early morning hours between 4 and 9 a.m.  This will result in less water wasted through evaporation and will limit the amount of time that the foliage will stay wet.  Plants are accustomed to being wet from dew during the early morning hours, so watering this time is best.

Where possible, utilize drip irrigation in your gardens and landscapes.  Soaker hoses or more complicated systems with drip emitters are extremely effective and are much more water efficient when used for shrub beds, flower or vegetable gardens, or newly established trees.

Although most disease problems are caused by fungi, there is a new group of virus diseases that are beginning to show up not only on commercial tomato plantings but in home gardens as well. While there are several viruses that will attack vegetables, the tomato spotted wilt virus has really caused a lot of problems the last few years.  

Tomato plants infected with tomato spotted wilt virus become stunted and often die.  Initially, leaves in the terminal part of the plant stop growing and often become distorted and begin to turn pale green compared to the healthy foliage.  In young leaves, the leaf veins thicken and turn purple, causing the leaves to appear bronze in color. 

Necrotic spots or ring spots are often found on the leaves and even the stems can appear streaked.  The infected fruit may contain numerous ring spots and blotches and is often misshapen.

Unfortunately, there are no protective sprays to prevent virus diseases.  It is spread by piercing, sucking insects such as thrips or aphids as they move from plant to plant in the garden. This disease is spread very similarly to the way mosquitoes spread malaria in developing countries.

The best thing to do is to carefully remove any plants that you suspect is infected with spotted wilt virus. Avoid brushing the foliage of the plant on near by healthy plants; likewise, be very careful as you move through you garden or when tying, staking, or working around your plants. People can spread the virus as well as insects!

The variety Amelia is a home garden variety that is not popular just yet, but is available through many company seed catalogs. Bella Rosa is another good selection for home gardens that has good virus resistance.

Another common dry weather problem that I expect to see more of this year than in the past several years is blossom end rot. Blossom end rot is not a disease but rather a physiological disorder resulting from calcium deficiency. This disorder is marked by a dry black leathery rot at the bottom (blossom) end of the fruit, hence the name blossom end rot.

The best solution to blossom end rot problem is to make sure you keep the garden well limed with agricultural or dolomitic lime (this ensures that there is adequate levels of calcium in your garden soil). During dry weather plants cannot take calcium up out of the soil, so keeping plants well watered by using drip or soaker hoses will help to reduce the incidence of blossom end rot.  

I also recommend using a good layer of mulch such as pine or wheat straw, shredded newspaper, or other organic mulch.  The mulch will help to hold water in the soil around your plants and will help to keep the soils moisture at an even moisture level as opposed to being wet then dry then wet again. It will also help to reduce the amount of water it takes to provide your plants with adequate moisture. 

The mulch and supplemental watering helps to ensure that the calcium that is in the soil is able to be taken up and used by the plant.  The tendency is for potted or container grown tomatoes (what I call patio gardens) as well as those grown in raised beds suffer blossom end rot much more frequently than tomatoes grown traditionally “in ground”.  This is because raised beds and containers dry out much more rapidly and often the potting media that we use is low in calcium to begin with.

If blossom end rot has already affected your garden, you will need to remove the effected fruit as they will not recover from blossom end rot. The effected fruit will serve only as an entry point for other disease and insect problems. While most fruit that have blossom end rot develop the disorder while they are very small, the larger fruit may still be used by simply cutting away the effected part.