Tomato Blossom Drop Causes, Control Methods

Introduction: Hello gardeners and farmers, this post will give a insght of Tomato blossom drop causes and control measures.  Blossom drop is the loss of flowers and this is usually preceded by the yellowing of the pedicel. Tomato blossoms are very sensitive to the conditions in their surrounding environment. Tomato blossoms can drop from plants without developing fruit. And if they are not fertilized accurately or if they are exposed to unusually high or low temperatures or humidity levels. However, tomato blossoms can also drop from tomato fruit if they are properly fertilized. What are we waiting for? Let’s get in to the details of Tomato blossom drop causes and prevention methods.

A guide to Tomato blossom drop causes, control methods

If you are a commercial tomato grower or home gardener, you must be aware of tomato blossom drop causes. Tomato blossoms are self-fertile, and a certain quantity of self-pollination of tomato flowers does occur. However, pollen does not move well by itself from the anther to stigma, as evidenced by the poor pollination seen in greenhouses when no pollination aid is given. Shaking by wind or by mechanical means can cause the release of the pollen, which drops down (the blossoms normally hanging downward) through the stamen tube to the stigma.

Causes of Tomato Flower Drop.
Causes of Tomato Flower Drop.

The best possible motion to release pollen is from a bee that “sonicates”. Sonication is the vibration of the wing muscles without flight, causing the whole tomato flower to vibrate, and a cloud of pollen to be released onto the bee’s body and also, onto the stigma. Without pollination, this stimulates fruit set, flower withers and dies. Tomato plants lose their blossoms for different reasons usually related to some kind of stress. The stress can be either nutritional, environmental or some combination of the two. Anything which interferes with the pollination fertilization process can result in abortion of flowers.

Causes of Tomato blossom drop

Many problems cause blossom drop can be difficult to control. Because they are related to temperature and plant stress, they are including;

  • The temperature range that is too high or too low
  • Relative humidity
  • Too Much Fertilizer
  • Inadequate Irrigation
  • Lack of pollination
  • Low or high soil moisture
  • Insect damage or disease
  • Heavy fruit set
  • Excessive wind or pruning

Temperatures that are too high or too low

Blossom drop can be attributed to several causes, most often related to either temperature or stress. Tomato plants drop their flowers under extreme temperature regimes, such as high daytime temperatures that mean above 85°F, high nighttime temperatures that mean above 70°F, or low nighttime temperatures that are below 55°F. Optimal growing conditions for tomatoes are daytime temperature range between 70°F and 85°F. While tomato plants can tolerate extreme temperatures for short periods, several days or nights with temperatures outside the optimal range will cause the tomato plant to abort flowers and fruit and focus on survival. Temperatures over 104°F for 4 hours can cause the flowers to abort. If nighttime temperature range fall below 55°F or rise above 70°F, or if daytime temperatures rise above 85°F, the pollen becomes tacky and nonviable, preventing pollination from occurring and causing the blossom to dry and drop.

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High temperatures – High temperatures during the summer are a general cause of tomato blossom drop. Tomato blossoms often drop from the vine without setting fruit when the temperature range during the day exceeds 85°F for several consecutive days. During the spring and fall cool nights with temperatures below 55°F can also cause your blossoms to drop.

Low temperatures – Low temperatures prevent tomato blossoms from developing properly and could cause them to produce sterile pollen. High temperatures can cause defects in tomato blossom pollen that prevent it from becoming fertilized and then producing fruit. The unfertilized tomato blossoms eventually dry up and drop from the vine. Sharp temperature swings from daytime highs to nighttime lows can cause tomato flower drop.

Relative humidity

The ideal humidity range is between 40 to 70%. If humidity is either too high or too low, it interferes with the release of pollen and with pollen’s ability to stick to the stigma and therefore pollination will not occur. If humidity is too low, hose the foliage during the day and this will both cool the plant and raise the humidity. This is not recommended in areas with high humidity or fungus diseases are present.

The ideal Relative humidity for tomato growth ranges between 40% and 70%. Relative humidity plays a major role in pollen transfer. If the Relative humidity is lower than the optimal range, it interferes with pollen release as the pollen is dry and unable to stick to the stigma. If the Relative humidity is higher than the optimal range, the pollen will not shed properly.

Too much fertilizer

Over-fertilizing tomato plants with nitrogen can lead to blossom drop. Applying nitrogen to tomato plants causes their stems and leaves to grow at the expense of flowers and fruit. Tomato plants that are over-fertilized with nitrogen often have thin and elongated stems that are poorly suited to supporting the weight of tomatoes.

It’s best to use a fertilizer with high phosphorus but moderate nitrogen when you set out tomato plants, and then to avoid fertilizing again until after fruit set begins.

High or low application rates of Nitrogen fertilizer can cause blossom drop. High rates of nitrogen fertilization encourage lush vegetative growth and inhibit flower production and pollination, resulting in poor fruit set. Low Nitrogen produces spindly vines with low food reserves that cannot support a crop.

Inadequate irrigation

These tomato plants have extensive root systems that are sensitive to dry growing conditions. Allowing the soil around tomatoes to dry out can cause their blossoms to dry out and drop from the vine before they can produce fruit. The roots of tomato plants have a deep growth habit that can reach 3 – 5 feet. Uniformly watering tomato plants so that the soil around the plant is uniformly moist to a depth of several feet helps promote a healthy root system.

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Lack of pollination

Tomatoes require some help to pollinate. Insects, wind or handshaking of the flowers is essential to carry the pollen from the anthers to the stigma. During extremes weather conditions, there are often no insect pollinators and when temperatures are too hot or too cold, insects aren’t active in the garden. Not as several blossoms are pollinated. Along the same lines, without proper humidity that is 40-70%, pollen has difficulty releasing or sticking.

Low or high soil moisture

Tomato plants have deep roots that can penetrate up to 5 feet. Low soil moisture stresses and weakens the tomato plants. The root zone must be kept uniformly moist throughout the growing season to develop a large root system and reduce plant stress.

Insect damage or disease

Apply good cultural practices and treatments for the disease as soon as symptoms appear. Fungal diseases, for example, botrytis or heavy bacterial spot or speck pressure can often cause flowers to abort.  Growers must use adequate cultural practices to control insects and diseases.

Heavy fruit set

When a tomato plant has too many blossoms, the resulting tomato fruits are all competing for the limited food supplied by the crop. The tomato plant will automatically abort some flowers. Once the initial crop is harvested, the problem must subside.

Excessive wind/pruning

Excessive wind can desiccate flowers and physically knock them off, reducing fruit set. Excessive pruning can reduce the amount of energy the tomato plant produces and thus can reduce flower production and fruit set.

Tips for controlling Tomato blossom drop

Tips for Controlling Tomato Flower Drop.
Tips for Controlling Tomato Flower Drop.
  • Select the right tomato variety for your climate. The tomato variety “Early Wonder” matures extra-early for areas with late summer. “Carmello,” “Black Cherry” and “Golden Sweet” are good choices for cool areas. “Black Krim” and “Grape Tomato” varieties set well, even in the very high summer heat.
  • Plant tomatoes when night temperature ranges are consistently above 50 degrees. Tomatoes produce best in daytime temperatures between 70 and 85 degrees but will tolerate extreme temperatures for short times. Tomato plants farming at the wrong time of year are more likely to suffer blossom drop. Some weather problems could be avoided by planting early or late-blooming varieties.
  • Spray tomato foliage with a fine mist from a garden hose when the humidity drops below 40 percent. High or low humidity prevents pollination, causing bloom drop and do not use this technique when humidity is high or if fungus diseases are a problem.
  • Don’t overdo the fertilizer and tomatoes should not be fed every week. You can add some balanced fertilized when the fruit forms. However, keep in mind that fertilizers high in nitrogen will encourage the plant to grow more foliage and not more fruit.
  • Make sure that tomato plants are healthy. You must always apply good cultural practices and treat your plants in case a disease appears.
  • Use a shade cloth over plants when daytime temperature ranges rise above 85 degrees. Also, use row covers or plastic tunnels when temperatures drop below 60 degrees. Keep tomato plants in the ideal growing temperature range to promote good pollination.
  • Provide enough water to maintain the root zone moist throughout the growing season, but not wet. Too much or too little water contributes to blossom drop and uneven growth of tomato fruit. Water tomato plants once or twice a week, providing at least 1 to 1 1/2 inches of water each week.
  • Fertilize tomatoes with a low-nitrogen fertilizer for example 6-24-24 or 8-32-16 at a rate of 1 pound per 100 square feet of garden. Avoid using ammonia fertilizers or urea on tomato plants. High or low nitrogen could cause a bloom drop.
  • Utilize a blossom set hormone when the weather is cool. Blossom set hormones to allow tomato fruit to set without pollination, but the fruit is often misshapen with few seeds.

Controlling methods of Tomato blossom drop

The controlling methods of tomato blossom drop can be given below;

  • Grow varieties suited to your climate
  • Ensure pollination
  • Used recommended N rates
  • Water deeply during dry weather
  • Control insect and diseases

To prevent temperature problems

While you can’t control your climate, you can control which type of plants you have in the garden. Always grow tomato varieties that are suited to your climate. Since inadequate temperature is the most general cause of blossom drop, you need to know which varieties to grow in your garden.

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Most tomato plants thrive when the daytime temperatures are in the range between 70°F (21°C) and 85°F (29°C). Many tomato varieties can tolerate higher and lower temperature ranges (even extreme ones) for a short period, if these temperatures persist for several days or nights, it will affect your plants. It can cause blossom drop in your tomatoes. With these extreme temperature ranges, the plant aborts setting the fruit and focuses on survival only. If the temperatures are truly extreme it could cause the blossom drop even after a few hours of such temperatures. To prevent this problem, it’s important to know the climate and to always plant only heat-resistant varieties.

For cooler climates, it is important to select early maturing tomato varieties if you wish to grow your tomatoes in spring. Some good tomato varieties to try ate Legend, Matina, Early Girl, Oregon Spring, Silvery Fir Tree, and Polar Baby.

It’s best to always select heat-tolerant (heat set) tomato varieties for places with long periods of humid and hot weather. Remember that high nighttime temperatures can affect tomatoes more than high daytime temperatures because they don’t allow tomatoes to rest. Some good tomato varieties for this type of climate include Solar Set, Sunchaser, Sunmaster, Heat Wave, Sunpride, Surfire, and Sunpride.

Avoid pollination problems

To avoid problems with inadequate pollination, make sure to always help tomatoes to pollinate. Certain conditions are required for proper pollination, such as wind, insects or handshaking. These are required to carry the pollen from anthers to the stigma.

Keep in mind that there are generally no insect pollinators in the garden during the weather extremes. To help pollination, it’s always useful to attract more bees to the garden by planting nectar-rich flowers near the tomato plants.

Humidity problems

Ideal humidity levels for tomato plants are in the range between 40% and 70%. In case the humidity is outside of this range (be it too low or too high), it will affect tomatoes and it may lead to blossom drop.

Inadequate humidity is problematic as it interferes with the release of pollen and with pollen’s ability to stick to the stigma. In these conditions, the pollination won’t happen.

If your garden has a high humidity level, you should only grow specific tomato varieties that are not affected by high humidity. Recommended tomato varieties include Flora-Dade, Eva Purple Ball, Grosse Lisse, Moneymaker, Taxi, Jubilee, Sun Gold, and Yellow Pear.

Controlling watering problems

Tomato plants need a lot of water. It is very important to water them regularly so they can thrive. Regular watering will prevent several problems, including the blossom drop. Tomatoes require to be watered at least once per week during the dry weather. Make sure to always water tomatoes deeply.

Keep in mind that tomatoes have deep roots. Sometimes the roots go down as deep as five feet. It means that you always require to deep water your tomatoes. Shallow watering is simply not enough and it can stress and weaken your plants.

That’s all folks about Tomato blossom drop causes and its control measures. You may be interested in Small Gardening Ideas for Indians.

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