Blossom End Rot

One of the current issues plaguing the home gardener right now is blossom-end rot. Often mistaken for a disease, it is primarily a physiological problem. No bacteria or pest causes blossom-end rot, rather the plant cannot get what it needs: calcium. This disorder is caused by a lack of calcium uptake from the soil and resulting in little transfer to the fruits during dry weather. Because we have experienced a much lower rainfall this season, you may be seeing the signs of this now.

Symptoms may occur at any stage in the development of the fruit, but most commonly are first seen when the fruit is one-third to one-half its full size. As the name of the disease implies, symptoms appear only at the blossom end of the fruit. Initially a small, water-soaked spot appears, which enlarges and darkens rapidly as the fruit develops. The spot may enlarge until it covers as much as one third to one-half of the entire fruit surface, or the spot may remain small and superficial. Large lesions soon dry out and become flattened, black, and leathery in appearance and texture.

Blossom-end rot happens when a number of conditions come into place.  The disease is especially prevalent when rapidly growing, succulent plants are exposed suddenly to a period of drought. The roots fail to obtain sufficient water for calcium to be transported up to the rapidly developing fruit, causing the bottom of the tomato to rot. Other factors include a pH out of range and damage done to the roots from cultivation too closely.  Soils that contain excessive amounts of soluble salts may predispose tomatoes to the disease, for the availability of calcium to the plants decreases rapidly as total salts in the soil increase.

To manage blossom-end rot take these steps:

·  Water consistently if there is a lack of rain, about one inch per week.

·  Add mulch to your garden, this conserves moisture.

·  Use fertilizer low in nitrogen, but high in superphosphate, such as 4-12-4 or 5-20-5

·  Do not spray any type of pesticide, as this is not a symptom of insect, bacteria, or fungi    damage. Pesticides are  ineffective on blossom-end rot.

·  Consider a soil test. This will give you a complete analysis of what your garden needs and will give you a head start for the next growing season.

For more information on blossom-end rot, contact the Penn State Master Gardener Helpline at 570-963-6842, or email us at LackawannaMG@psu.edu and request a free copy of the blossom-end rot publication.

Steve Ward

Master Gardener Coordinator

Penn State Cooperative Extension in Lackawanna County

Tomatoes, 2010

In just a few weeks it will be time to plant tomatoes. When you buy transplants, choose plants that have a nice green color on the lower leaves. Choose plants with a thick stem. Avoid plants that have blossoms or small fruit unless they were grown in a 6” pot or larger. If you have not added calcium lime for a few years, apply it when you till your soil. Lime will help prevent the tomato fruit from getting blossom end rot. When you transplant tomatoes into the garden, plant them deep. Tomatoes will develop roots from the parts of the stem that are underground. Apply fertilizer soon after planting.

We are concerned about late blight being a problem in tomatoes again this summer. The summer weather will determine if late blight will be a problem in 2010 or not. It has been a problem for growers in Florida again this winter. If we have a cool wet summer, expect late blight to be active. Late blight does not do well when the weather is hot and dry. Fungicides containing chlorothalonil are effective at protecting tomatoes. If you use a fungicide, it will have to be on the foliage before the blight attacks and thorough leaf coverage is critical.

Also, every Saturday, through May 22nd, we are offering a Spring into Gardening Workshop at Bill’s Ace Hardware, Route 435 Daleville, PA. The Master Gardeners will answer your gardening questions from 11 am – 2 pm. Plus, at noon we will have demonstrations on various seasonal topics. This program is free and open to the public. Here are the upcoming topics:

• May 1st - lawn care basics
• May 8th - landscaping for the birds
• May 15th - composting
• May 22nd - home food preservation basics
  
  

For more information contact your local cooperative extension office. In Lackawanna County call 963-6842 and ask for the Garden Helpline or email LackawannaMG@psu.edu


John Esslinger, Extension Educator
Penn State Cooperative Extension
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