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The plant in our office started to have this strange marks, what can be the reason for that kind of marks? how can we cure the lovely plant?
Yellow leaf spots have various shapes, depending on the cause. Downy mildew starts with angular pale yellow spots. In cucumbers (Cucumis sativus) and other cucurbits, powdery mildew causes pale yellow spots followed by powdery white patches.
The location of the yellow spots may help you determine the cause of the symptom. Some diseases, such as powdery mildew, cause spots on older leaves first and then spread to younger leaves. Yellow spots from powdery mildew can occur on upper and lower leaf surfaces. Downy mildew spots occur on the upper sides of leaves between leaf veins that give the spots their angular shape.
Now lets jump into the causes :-
1 -Moisture Stress
Over-watering or under-watering are the most common culprits when a plant's leaves turn yellow. If plants don't receive enough water, they drop leaves to prevent transpiration (essentially, a plant's way of sweating) and conserve water. Before they drop, though, the leaves will typically turn yellow. Too much water can be just as damaging to leaves. When the soil doesn't drain well, an overdose of water leaves the soil waterlogged and root systems can literally drown. Without oxygen, roots start to die.
As many plants age, the lower leaves will turn yellow and drop off.
However, to solve this case, don't worry. If the plant becomes too leggy, consider trimming back the main stem to promote new growth and bushiness.
Now let's first understand what a cold draft is. A cold draft is a current of cold air being drawn indoors.
A plant sitting near it is giving off more heat than it receives from the room. Remember, heat travels from places of higher temperature to places of lower temperature.Cold drafts on tropical plants will often cause the leaves to turn yellow and drop.
To solve this problem, particularly If your plant is near an air-conditioner vent in summer or a drafty window in winter, move it to a less turbulent place.It's also a good idea to mist tropicals that you're overwintering to increase the humidity.
4- Lack of Light
A plant that is yellowing from a lack of light will typically yellow on the side that is away from the light source.
To solve this, move the plant to a sunnier location and see how it does. If window light is tough to come by in your home-especially in winter-you might need to rig up an artificial plant light or two.
5- Nutrient Deficiency
This can be caused by too much calcium in the water if you're using hard water, or by a nitrogen deficiency.If this is the problem, the plant's top leaves may be the first to go yellow.
However to solve this issue, since it is species specific, its important to diagnose the problem firstly and them take some remedies.
If your plant has a viral infection, it might show up as blotchy, spreading yellow patches on leaves throughout the plant. This may be accompanied by deformed leaves and stems, as well as discolored flowers.
To solve this , discard any plants that you suspect are infected since viral infections can not be treated.
7- Fungal infection
If caused by a fungus, there is nearly always fungus growth of some type in the spot, particularly in damp weather. This fungus growth may be tiny pimple-like structures, often black in color, or a moldy growth of spores.
To solve this, you can use sulphur(in dust form) and milk.
Sources - https://www.thespruce.com/reasons-for-yellow-leaves-on-houseplants-4150680 https://www.hunker.com/12140067/how-to-diagnose-cause-of-yellow-spots-on-leaves www.uky.edu/Ag/PAT/cat1/leafdis.htm
Its Chlorosis, degradation of Chlorophyll. gradually it will lead to necrosis. it might be due to lack of nutrients, especially manganese, zinc or iron. it might also be due to poor drainage or root damage. provide more space for the roots to grow. Treat soil by providing nutrients. your problem should solve.
Troubleshooting Black Tomato Leaves
One of the most head-scratching things for gardeners is when their tomato plant leaves start showing signs of a problem. It’s easy for someone to become overwhelmed when reading through all of the conditions that could be the culprit of black spots.
What Can You Immediately Rule Out?
If you see black leaves in your garden, it is possible to immediately rule out mosaic virus, nutrient deficiencies, and blossom end rot.
- Tomato mosaic virus — closely related to tobacco mosaic virus — appears as mottled leaves (a mosaic appearance), stunted eaves, curled leaf edges, and uneven ripening of fruits.
- Nutrient deficiencies show as yellowing of the leaves or stunted growth of the vegetables.
- Blossom end rot appears as black, leathery patches on the bottom of fruit. The leaves and stems are unaffected.
What Do You Need to Consider?
Are you planting tomatoes and noticing black spots on their leaves? Are you struggling to figure out what is causing the demise of your plants? Don’t worry. Chances are the answer to your woes is one of the following pathogens.
If there's one crabapple problem that most people have seen or experienced with their own trees, it's apple scab.
What to look for
Symptoms often first appear in late spring, when you’ll see dark blotches (called lesions) on leaves, as well as a dark, velvety growth over the leaf surface. In summer, leaves turn yellow and fall prematurely, often leaving the tree mostly, or even completely, defoliated. Infected fruit are usually deformed and develop circular, rough spots on the skin. Fruit rot quickly and fall before ripening.
Apple scab is caused by a fungus called Venturia inaequalis that’s found on most types of apple trees, especially in the Midwest. As with most fungal diseases, it first develops when conditions are humid and not too hot (spring and early summer).
Do nothing – A healthy crabapple can withstand annual defoliation for many years, although it will eventually weaken the tree and make it more vulnerable to other diseases and pest infestations. If the tree retains most of its leaves and you don’t mind the sparse leaf coverage in summer, doing nothing is a reasonable option.
Spring fungicide applications – For trees that are highly susceptible to the apple scab fungus, annual fungicide treatments are the best option. These treatments are applied as leaves emerge throughout spring and early summer, and can protect them from infection by fungal spores. However, it does not “cure” the disease.
Dispose of all debris from infected trees – Carefully clean up all fallen branches, leaves, fruit and twigs, bag them, and put them in the trash. Good sanitation is essential to minimize the likelihood of fungal spores re-infecting the tree next spring.
Ensure the tree isn’t crowded – Late winter pruning can help open up the canopy and improve air circulation, as can pruning back any nearby shrubs or trees that are crowding the crabapple.
Plant scab-resistant crabapple cultivars – It may be best to remove a tree that succumbs to apple scab each summer and replace it with a scab-resistant one. The following crabapple varieties have been found to develop only slight to moderate scab infections: Adams, Baskatong, Brandywine, Callaway, David, Dolgo, Donald Wyman, Malus floribunda, Henry Kohankie, Henningi, Jewelberry, Ormiston Roy, Professor Sprenger, Malus seiboldi var. zum cultivar Calocarpa, Silver Moon, Sugartyme, Malus tschonoski, Weeping Candy Apple, White Angel, and White Cascade.
Cultural Brown Spot Causes
Brown spots and yellowing leaves can come from a number of causes related to the care you give your dumb cane. Brown spots or patches at the margins of the leaves can be caused by over-fertilization -- the leaves can be burned by the soluble salts in the product. Plants should be watered until water comes from the bottom of the pot to leach excess fertilizer from the potting mix. On the other hand, leaves that turn yellow and are smaller and closer together on the plant's stems indicate poor nutrition, particularly low nitrogen. When dumb cane wilts and turns yellow from the bottom up, it needs to be watered more regularly.
It appears your tree may be suffering from peach leaf curl.
Peach leaf curl is caused by the fungus Taphrina deformans and occurs wherever peaches are grown. The fungus causes the growing cells at the leaf margins to multiply quickly and randomly, which results in the puckered, curled, distorted appearance. Often times the color of the leaves vary from shades of green and yellow, to pink, orange, and purple. Spores are produced on the surface of the leaf as the leaf matures, giving it a dusty appearance. Fruit can be infected and will either drop prematurely or form distortions on the surface.
The spores overwinter in bark crevices and around the buds. Primary infection occurs from bud swell until the first leaves fully emerge. Rains wash the spores into the buds and long periods of cool (50 to 70°F), wet (>95% humidity) weather are ideal for infection little infection occurs below 45°F. If warm temperatures follow bud swell and leaf development is rapid, infections are rarely established, even if rains occur.
Sanitation and cultural controls are not effective for this disease. Some peach cultivars have been bred for resistance to this disease, so resistant cultivars and fungicides are the primary management tools.
Copper sprays during tree dormancy, as well as in-season applications, are important. Once established in a group of trees, even radical pruning to remove infections will have only modest success controlling the disease.
About Yellow Veins on Leaves
When a plant’s foliage creates insufficient chlorophyll, the leaves become pale or begin to yellow. When the leaves remain green and only the veins are turning yellow, the term is called veinal chlorosis.
Interveinal chlorosis is different than veinal chlorosis. In interveinal chlorosis, the area surrounding the leaf veins becomes yellow in color while in veinal chlorosis, the veins themselves yellow.
Along with this major difference, the causes of chlorosis differ. In the case of interveinal chlorosis, the culprit is often a nutrient deficiency (often an iron deficiency), which can be diagnosed through testing and usually fairly easily remedied.
When a plant has leaves with yellow veins due to veinal chlorosis, the culprit is often more serious.
Why are my tomato leaves turning yellow?
As a tomato plant grows, it is often thought that it is in the plant’s nature for the lower leaves to turn yellow and die off. However, that is simply not true according to Joe Masabni, Ph.D., Texas A&M AgriLife Extension Service vegetable specialist in Dallas.
Masabni, an assistant professor in the Department of Horticulture in Texas A&M University’s College of Agriculture and Life Sciences, explains that a healthy plant that is well maintained and not stressed by disease or nutrition should have green leaves from the bottom to the top.
Typically, yellowing leaves are a result of a nutritional imbalance or disease outbreak, but other causes can play a part.
Nutrition can be a cause for yellowing leaves on tomato plants
“Nitrogen is the most common cause, because people generally don’t fertilize tomatoes enough,” Masabni said.
Tomatoes are heavy feeders, meaning the plant requires twice the amount of fertilizer that a cucumber needs, and even four times the amount as beans, he explained.
If you don’t fertilize enough with nitrogen, the older leaves will begin turning yellow and, in many cases, may fall off. The older leaves turn yellow because they are providing their nitrogen to the younger leaves to survive.
Yellowing of leaves can also be the result of an iron deficiency in the plant, but this will be most prominent in the youngest leaves. A magnesium deficiency however will produce yellowing that looks more like speckles or spots on the older leaves.
“Those three – nitrogen, iron and magnesium – are the most common nutritional deficiencies growers should pay attention to and fertilize regularly for,” Masabni said.
It is good to keep in mind, that with the use of a lot of fertilizer, the plant will also require a lot of water.
“There is no perfect recipe for how much water your tomato may need, but a good rule of thumb is to do a moisture test where you place a finger several inches deep in the soil to test for moisture near the roots,” he said. “If it feels dry, it’s time to water, and as the tomato plants get closer to full maturity, they will require more and more water. Better yet, buy a soil moisture meter and use it regularly as a guide on when to water.”
Diseases may present with yellow leaves
Leaf symptoms of early blight are large irregular patches of black, necrotic tissue surrounded by larger yellow areas. (Photo courtesy of Aggie Horticulture)
Texas is a prime location for fungal diseases in tomatoes, simply due to the heat and humidity that are common in the state. Because these conditions are ideal for spreading diseases, Masabni suggests using a fungicide protectant on a regular basis, once every seven to 10 days, and up to 14 days in a dry year.
“Spray on a schedule whether you think you need it or not,” he said.
Fungicides are typically used as protective and not as a curative measure for fungus. So, this is a proactive approach that gardeners will want to start before seeing signs of disease to protect the plants from developing one. Once you can see the disease, it is often too late.
Powdery mildew is first noticed on older leaves as a yellow spotted appearance, that upon closer inspection has a whitish-gray powder on the surface.
Most fungal and bacterial diseases cause some kind of yellowing, he explained.
The most common fungal disease seen in Texas is powdery mildew or early blight, which starts from the bottom of the plant and moves up as the leaves die off.
Physiological disorders can produce yellowing of the leaf
Salt damage – not just table salt or sodium chloride, but any excess mineral – can result in yellowing.
If you are growing tomatoes in a container and your water contains a heavy amount of salt, once in a while water the container until it leaches out, so the salt can run through the soil and flush out of the container. This will help in preventing buildup of those salts within the container itself.
Use caution with herbicides
“Gardeners should avoid Roundup near the vegetable garden because tomatoes are super sensitive to Roundup,” Masabni said.
Roundup injury to tomatoes creates a bleaching effect from the inside to the outside of the leaf and affects the newest growth of the plant such as the youngest leaves and shoots.
Vegetable problem solver and maintenance
On the Aggie Horticulture website, the vegetable resources link provides a vegetable problem solver where you can look at different common problems you may encounter in Texas.
“The bottom line—any form of yellowing is not good,” he said.
Even if you don’t know the cause, remove any yellow leaf and throw it away in case it is diseased so it will not spread and infect others. Remove that leaf, spray a fungicide and hopefully the problem will be resolved by early diagnosis. When removing leaves, be sure to remove them with a clean hand and properly dispose of the leaf. Wash your hands thoroughly before you continue working on other healthy plants to avoid spreading any disease between plants.
Also, ask yourself if you have been fertilizing regularly. Does the plant look tall enough or is it the same height as a month ago, which may mean you need more fertilizer?
Placing a fertilizer solution on the end of your hose and washing off your plant from top to bottom on occasion will also simulate a rainfall situation, he explained. This will be especially helpful in a dry year, when mites may become a bigger issue. Washing the plant with water will wash off the mites, and clean and cool the plant, all while fertilizing it.
For more information on vegetables and gardening resources, visit the Aggie Horticulture website.
Causes of Hoya Leaves Turning Yellow
Sometimes, it can be difficult to determine why Hoya leaves are turning yellow. Do not worry, this article will help you by showing a number of common causes to look out for. You will also learn how to fix the issues.
Like all plants, Hoya needs light to engage in photosynthesis. Photosynthesis converts light, oxygen, and water into the energy needed by the plants to grow and bloom. Too much light or nothing at all can compromise the plant’s health.
Avoid keeping your Hoya plant outdoors for a long time. Intensive and direct ultraviolet rays from the sun can scorch the plant.
Prolonged sun exposure can even result in sunburn (brown and dry streaks) and make the plant limp.
Likewise, do not place your Hoya plant in a dark area. Aside from photosynthesis inhibition, inadequate light interrupts chlorophyll production.
Lack of chlorophyll results in yellowing because it is the green pigment in the leaves.
How to Fix
To give your Hoya plant the appropriate amount of light it needs, here are a few tricks:
⦾Place the Hoya plant in an area that receives partial shade. You can put it in east- or west-facing windows.
⦾If you put the Hoya plant outdoors, make sure it is not receiving direct light. Shade the plant with a cloth or a taller plant.
⦾Artificial lighting is a good alternative source of light. You can hang two regular fluorescent bulbs 10 to 12 inches above the highest part of the Hoya. Turn on the lights for four hours or more, depending on the brightness of the area.
⦾If the plant got a sunburn, remove the affected part. This method will stop wasting nutrient supply to these hopeless leaves. And divert them to the growing ones instead.
Another common reason behind the yellowing of the Hoya leaves is improper watering. Do not underwater or overwater the plant as it can lead to problems.
Do not let the Hoya plant sit in a drought-like environment, especially for a long time.
Plants need water to move nutrients up to foliage and make food. Thus, an insufficient amount of water will make the leaves wilt, dry, and yellow.
Meanwhile, an excessive amount of water reduces oxygen in the soil, damage, and even rot the roots.
Plants with injured roots will not take up moisture from the soil. This incident further results in leaf discoloration, loss of vigor, and stunted growth of the plant.
How to Fix
These tips will help you achieve the proper watering techniques for your plant:
⦾Water your Hoya plant only when the surface of the soil is completely dry. Check the soil moisture by lightly poking the growing medium or using a moisture meter. Around two or three inches from the topmost layer of the soil should dry out before watering again.
⦾Consider these several factors that influence plant watering:
- Measurement of the plant – The larger plants need more water than the smaller ones.
- Types of the pot – Plastic containers usually dry out more rapidly than the clay types.
- Location of the plant – Moisture in soil under a bright environment tends to evaporate faster.
- Time of the Year – In cold months, plants require less frequent watering compared to the warm season.
⦾Water the growing media several times if it is extremely dry. This method will rehydrate the soil that separates from the sides of the pot.
⦾Ensure proper drainage to avoid overwatering. Drill the base of the pot to make additional holes. Frequently pour off the collected water in a saucer at the bottom of the pot.
Proper watering techniques are not enough to make the Hoya plant thrive. They should also receive filtered water that is free of harmful chemicals.
The effects of getting adverse substances will not show off overnight. It will eventually build up and accumulate over time.
Sooner, you will notice yellow or dark spots in the leaves of the Hoya plant.
The discoloration of the foliage happens because chemicals inhibit photosynthesis.
Photosynthesis is a vital process for the plant because it is the way of making their food.
How to Fix
Follow these methods to ensure that your Hoya Plant is receiving quality water:
⦾Hold back using tap water because chemicals such as fluorine naturally occur in it.
⦾Let the water sit for a few days if tap water is all you have. This step will make some amount of chlorine evaporate.
⦾Water the plant with rainwater, melted snow, or distilled water.
⦾Install a filtering system. It’s an investment for both the humans and plants that will last.
⦾Give your plant lukewarm water. Extremely hot or cold might harm them.
⦾Get your water a quality check by a local authority. This procedure will help you find out more about your water. Additionally, results will include information about the substances in your water.
A Hoya plant thrives well in an environment with temperature ranging from 68°F to 75°F (20°C to 24°C).
Keeping them in a condition with extremes of temperatures can result in problems. (Source: University of Florida, IFAS Central Florida Research and Education Center)
A too high-temperature may cause some plant processes to malfunction. This includes rapid transpiration that can lead to water loss.
Meanwhile, severely cold temperatures can cause chill damage. Ice crystals form within the tissues of the leaves, expand and inhibit photosynthesis.
Both extremely cold and hot temperatures result in the reduced rooting, shallow growth, as well as yellowing of the leaves.
How to Fix
Follow these methods to maintain the ideal temperature range for Hoya:
⦾Check if your Hoya plant is in a spot where temperature can drastically change. Places like windowsill are great for summer but get drafty in the cold season.
⦾Increase warmth or coldness of the area using a cooling or ventilation device.
⦾Automatically regulate the temperature of the area using a thermostat.
⦾Follow these procedures if your Hoya becomes cold-damaged (Source: University of Florida, Gardening Solutions):
- Water the plant to defrost the soil and supply moisture to the injured plant.
- Stop fertilizing for a while. Feed the plant again with fertilizer after the cold months.
- Do not prune the damaged parts. This affected foliage will help insulate the plant.
While fertilizing your Hoya plant is beneficial, you might overdo it.
Excessive amounts of fertilizer result in a build-up of excess minerals and salt. This formation alters the pH of the soil, making the nutrients less available to the plant.
Moreover, too much fertilizer can lead to the sudden growth of the plant with poor root structure. It can even result in the toxicity that slows the development of the plant.
Never overfertilize your plant as it can harm them and make the leaves yellow. Severe cases may even result in death.
How to Fix
Here are a few methods you can follow to avoid overfertilizing your Hoya:
⦾As the Hoya plant grows, feed it with fertilizer two to three times a month. Liquid fertilizer with a 2:1:2 or 3:1:2 ratio is usually ideal for them. When it becomes established, go for high phosphorus fertilizer to encourage blooming.
⦾Consider the soil volume and light intensity when feeding your houseplant. Both high light intensity and large pots require more fertilizer, otherwise less.
⦾Here are a few ways you can follow if your Hoya Plant has symptoms of overfertilization:
- Reduce the amount of fertilizer or stop feeding the Hoya Plant for a while until it recovers.
- Thoroughly water the soil several times to wash off excess salts.
- Ensure that the water drains out of the base of the pot when removing mineral formation.
Plants also suffer from malnutrition if they are not getting the appropriate amount of nutrients. The yellowing of the leaves is a result of low levels of certain nutrients.
These nutrients include nitrogen, potassium, and magnesium. Stunted growth and deformation of the leaves are also indicators of nutrient deficiency.
Do not worry, the Hoya leaves can bring back its green appearance if it regains the nutrients loss.
How to Fix
Follow these procedures to help your Hoya recover from nutrient deficiency:
⦾Give the Hoya plant sufficient amounts of water, light, and fertilizer. These factors are the main sources of the nutrients for the plant.
- This test will help you determine what nutrients are too much or too little from your soil.
- Results will also provide information regarding the pH level of the soil. The ideal pH level that makes nutrients most available to plants ranges from 5.5 to 7.0. It is also where good bacteria work best in the soil. You can use some products to adjust the pH level of your soil.
⦾Check if the soil temperature is within the optimum range for nutrient uptake. A temperature ranging from 65°F to 75°F (18°C to 24°C) is ideal for most plants. To measure the temperature, get a typical thermometer and push it as deep as possible in the soil.
If you notice that the Hoya suddenly looks unhappy, you can suspect it is because of pests. Your plant may experience light to severe infestation of pests.
Watch out for some pests that love lurking at Hoya Plant. Insects like mealybugs, mites, and scales are usually from an infested plant brought inside the house.
Meanwhile, aphids, moths, fungus gnats, and thrips fly from outdoor plants to the Hoya Plant.
These insects suck the plant juices and secrete honeydew in the leaves. Honeydew is a sticky liquid that encourages mold production.
The mold blocks the sunlight from entering leaves, thus inhibiting photosynthesis.
All these results in the wilting, drooping, and yellowing to browning of the leaves. Severe cases can also lead to stunted growth and even death of the plant.
How to Fix
Solve the pest problems with these helpful procedures:
⦾Clean the leaves of the Hoya plant with a cotton ball dipped in alcohol. Wipe both the top and bottom part of the leaves.
⦾Gently wash the leaves of the Hoya plant, Using a mixture of mild soap and water
⦾Manually handpick the insects. This only works for larger insects like mealybugs.
⦾Remove the damaged parts by using a sharp shear or scissor. Disinfect the tool before and after pruning.
⦾Spray the plant with appropriate insecticides. Make sure that the pot has proper drainage when doing this as phototoxicity may occur.
⦾Isolate the infected plant to prevent the spread of the pests to the nearby plants.
⦾Discard the Hoya plant if it is severely damaged and seems incurable. Burn or bury it deep down the soil. Do not put this plant in a compost pile.
- Carefully examine the plant before purchasing it. Never bring an infested plant indoors.
- Do not keep your Hoya Plant in stressful conditions. Overly wet soil under low light invites pests to breed.
- Do a regular inspection of your plant. Make the checking of the plant after the watering session a habit so you will not forget it. This trick will help in preventing insects before they infest.
Why Would Hibiscus Leaves Turn Yellow With Black Spots?
Black spots and yellowing leaves on hibiscus often indicate a fungal infection or leaf scale. The fungus normally clears as the weather warms, but scale sometimes requires the use of an insecticide.
Fungal infections are most common on hardy hibiscus that remains outside all year long. It often begins as temperatures start to warm. Dew forms on the leaves early in the morning and remains in place for several hours, providing the ideal conditions for the black fungus to grow. Removal of excess foliage and falling leaves helps to improve air circulation to dry the moisture more quickly. Some fungicides are safe for use on hibiscus, but the problem usually stops when the temperatures get warmer and the leaves naturally turn yellow and fall from the plant.
Scale insects attach to the hibiscus leaves and feed through a straw-like tongue they insert into the structure. Once they attach, they do not move, creating the appearance of spots, and the leaves eventually yellow, die and fall from the plant. The leaves secrete honeydew around the opening the insect creates in the leaves, which can attract mold spores to create larger black or brown spots. Because the honeydew is food for ants, they protect the scale insects from many of their natural predators. Horticultural tape around the base of the plant helps to keep ants away, making it easier to prevent scale on the hibiscus.
8 Reasons Plant Leaves Turn Yellow
Spring and early summer is an exciting time for the gardener. Seeds are sprouting, transplants are beginning to establish themselves, and the garden–your investment in sweat and time–is taking off.
While walking through the garden, you may at some point discover yellow leaves on the plants. The leaves can tell a story, and when they’re yellowing, the plant isn’t producing enough chlorophyll. As you dig deeper, the leaves can also tell you why.
Lean in and take a closer look at your plant and the soil around it. Among other issues, you may notice pests getting started, or determine whether it’s receiving too much or too little water. With close observation, you can pinpoint and treat the likely problem.
What are 8 reasons plant leaves turn yellow? What can help correct each issue, and keep your plant and garden thriving?
Watering issues are generally the most common cause of yellowing leaves. When your plants are overwatered, the performance and vigor decrease. Oxygen is being pushed out of the soil, and the roots are simply “under aired” and suffocating. With little air, the roots will begin to drown and rot. Overwatering also leads to various fungal diseases.
Check the moisture level in the soil. Dig down a few inches near the stem of the plant. Take a small handful of soil and squeeze it. If it’s moist or cool to the touch, it doesn’t need more water at the moment.
The mature leaves on overwatered plants are brownish-yellow and begin to wilt, look limp, or have a mushy feel. Black spots and lumps may appear on the stem and leaves of the plant, and the fruit will crack due to too much water.
First, reduce the watering frequency. Water deeper and less often. Also add air to the soil by poking holes deep around the root zone with a screwdriver. If your plants are in a container, drill a hole in the bottom of the pot and make sure the soil drains well.
While overwatering plants is just as harmful, underwatering will sometimes kill your plants much faster. Dehydrated plants look “off” and lack vigor. Performance declines with under watered plants, and fruit may not form properly.
Plants normally wilt during the heat of the day because they get hot and they can’t move out of the sun. To determine if your plants aren’t receiving adequate water, check the soil a few inches below the surface either in the morning or in the early evening. If it feels warm or dry to the touch, it needs water.
When you work out a proper watering schedule, keep in mind the proper amount of water varies based on climate, month, and temperature. Continue to monitor your plants and check soil moisture levels throughout the growing season.
The newest, youngest leaves are wilting and turning yellow. With tomatoes, the plants may develop blossom-end rot.
Water deeper and less often. Plants benefit from deep watering rather than frequent light waterings. In fact, they prefer a good drink as opposed to a light shower. This encourages the roots to grow deeper, enabling the plant to access more nutrients in the soil and not dry out as quickly.
3. Cold Stress
Shifts in temperature–hot or cold–affects the health and color of leaves as well. When prolonged cool temperatures or late spring cold drafts occur, your plants–especially tender vegetable plants such as tomatoes and cucumbers–may lose their color.
Keep an eye on evening temperatures as well. When a late frost is forecasted, cover your plants for the night.
Yellowing leaves, and in some cases, the edges appear burned.
Patience and time will solve most issues. Good sunny days will bring your plants back to life and chlorophyll will return to the leaves. In case of frost, use a frost blanket or bucket to cover your plants in the evening.
Yellow leaves appear when the plant receives too little sunlight, and with partial shade varieties, too much sunlight. Leaves are the solar panels of the plant the place where their energy is produced.
When a plant becomes thick and bushy, it sometimes blocks light from reaching inner and lower leaves. These leaves cannot photosynthesize and chlorophyll production comes to a halt. Since the leaves are non-productive, the plant no longer needs them.
Partial shade plants and cole crops such as lettuce are susceptible to burning and turning yellow in the hot summer months. It’s best to plant these veggies (or flowers) in early spring or fall, or in partly shaded areas. However, if they’re already growing strong, try to give them a break from direct sunlight in the heat of the day.
Yellowing leaves on the bottom or inside of a usually thick plant. In cases of heat stress, leaves will yellow and burn in spots.
Simply remove non-productive yellowing leaves. The plant will be fine without them. On plants that don’t perform well in direct sunlight, screen them in the mid-afternoon to prevent burning. If they’re in a pot or container, move them to a more shady part of the yard when outside temperatures begin to soar.
5. Nutrient Deficiencies
One common reason a plant’s leaves turn yellow is the lack of essential nutrients in the soil. Plants lacking these minerals show different symptoms, but in general, they are off-color, lack vigor, or simply, not growing well.
Essential minerals are absorbed through the soil, and different plants have different nutrient requirements. Know what each of your plants need, and test your soil regularly to make sure it contains the right amount.
Signs & Corrections for 6 Essential Nutrients:
- Calcium – Leaves are yellow, and distorted with a “crisp” feel. With tomatoes, the plants may develop blossom-end rot. Correction: Test the soil and add lime if it’s acidic or gypsum if it’s alkaline. Alkaline soils are more common than acid soils in the Intermountain West.
- Iron – Leaves typically become chlorotic yellow in color with green veins. Plant growth is stunted and it’s usually first noticed on new growth. Correction: Test the soil pH level and lower it under 7.
- Nitrogen – Pale yellow leaves on new growth (usually at the top of the plant). It begins with the center vein and tips turning yellow first, and plant growth is usually stunted as well. Correction: Add manure-based compost or used coffee grounds to the soil.
- Magnesium – Leaves yellow with white stripes along still green veins. It usually first appears on lower limbs. Correction: Add compost or fertilizer rich in magnesium sulphate (commonly known as epsom salts) to the soil.
- Potassium – Leaf edges and tips yellow, and mature leaves may develop brown spots or yellow-brown veins. Correction: Add fruit and veggie rich compost to the soil, or bury citrus rinds at the base of the plant. A potassium specific fertilizer may be used as well.
- Zinc – Leaves appear lighter and discolored in-between large veins. Correction: Spray with kelp extract, or apply a fertilizer containing zinc.
Always work to improve the health of your soil. Mix compost and soil conditioners into the soil in the spring or fall, and add humate throughout the year. Turn it under the soil 4-6 inches. If it’s during the growing season, add it in-between rows and plants by scratching and mixing the top 2-3 inches with a long handled 3-prong cultivator. Also rotate your crops each year to help prevent pests and diseases, and to maintain a rich, fertile, growing environment for your plants.
Each individual nutrient deficiency may require a specific type of treatment (as noted above). Remember, test the soil to find the exact issue, and treat appropriately. When you treat with fertilizer, apply it directly to the soil as directed on the label so your plant can absorb the right amount of the nutrients it needs.
In general, we recommend adding a balanced nutrient fertilizer in the beginning of the growing season such as IFA Grand Champion All Purpose Fertilizer (16-16-16). It contains the essential macronutrients along with minor nutrients like iron, magnesium, zinc, and many micronutrients to help provide your garden a fertile base throughout the season. IFA Premium Garden Fertilizer (16-16-8) is a great option as well. Once your vegetable or flowering plants are well established, supplement the soil with Fertilome Blooming & Rooting Plant Food (9-58-8) to help produce more blooms and a heavier crop of fruit.
6. Over Fertilization
The garden doesn’t perform well when it lacks essential nutrients, but keep in mind, your plants can be overfed too. More is not always better. When the soil is over fertilized, the plants have difficulty absorbing all it needs and the pH level may sometimes change.
Leaves turn yellow or brown, dry out, and commonly fall down. More specifically with nitrogen, a plant with too much will grow an abundance of branches and leaves with little to no fruit production.
You could test your soil before applying any fertilizer. It’s not necessary, but it can help you start down the right path to determine what your soil needs and make a plan.
7. Fungal & Viral Disease
The leaves on your plants may also turn yellow and display additional symptoms if it has been infected with a fungal or viral disease. The signs and treatments vary depending on the disease type. You may even see various degrees of development. This helps you determine that it’s likely a disease.
Signs & Treatment for 3 Common Diseases:
|Curly Top – This virus, carried by the beet leafhopper, causes leaves to turn upward and yellow, purple-colored veins, premature fruit and stunts growth. Treatment: Check with your local extension agent to find out if beet leafhoppers have entered your area yet this season, and try preventative measures. Once your plant becomes infected, those parts need to be removed. The plant may still produce new growth and fruit, but it will no longer reach its peak size or level of production.|
|Early Blight – Your plant starts to show brown spots, then the leaves turn yellow and fall off. Treatment: Early blight is usually avoided by rotating crops annually (planting crops in different spots each year) and using fungicides.|
|Septoria Leaf Spot – High humidity, high temperatures and overhead watering can cause lower leaves to develop dark brown circular spots with a yellow ring. It’s one of the most destructive fungal diseases on tomato foliage and usually appears after the first fruit sets. Treatment: Rotate crops annually and avoid overhead watering. Some fungicides will help as well.|
Water properly to help prevent many fungal diseases. Avoid overhead watering and watering too much. Use either drip, furrow or flood irrigation, and soak thoroughly on a consistent basis rather than giving your plants a light sprinkling every day. This will encourage a healthy, deep root system.
Along with beet leafhoppers, there’s a number of additional pests infesting our gardens. Aphids, mites, earwigs, mealybugs, thrips, scale, or whiteflies–amongst many others–are all typically found around our fruits, flowers and vegetables.
The damage and symptoms shown by your plants may vary depending on the type of pest, but yellowing leaves are a common sign of most. Once you notice a problem, first find and identify the insect causing issues. When you’re closely observing your plants, peek on top and below the leaves. Look for additional symptoms, insects, and possibly, eggs. Also check darker, cooler areas such as under your lettuce. Earwigs and other bugs love to hang out in these places.
Regularly monitor your plants and treat pests early. You will notice changes to your plants before they become big problems.
Many options of treatment are available–chemical and organic–depending on the insect and your comfort level. However, washing your plants on a consistent basis with an insecticidal or horticultural soap is one effective, environmentally safe method to help prevent and treat many pests.
In any case, always be sure to keep weeds out of your garden. Weeds attract insects and diseases, and steal much-needed water and nutrients from your vegetables.
No matter the issue, help is only a click or visit away. If you’re having trouble reading the leaves and identifying the problem, take photos at various distances and share them with your local extension agent or IFA Country Store. Include at least one picture of the entire plant and a close-up of a single leaf (or pest) to help identify the issue and recommend treatment options.
Continue observing and caring for your garden. Healthy, thriving plants will reward you with all of your favorite summer fruits and veggies. If your plants are growing well with good color and normal sized leaves, kick back on the patio and enjoy your favorite summer beverage. You’ve earned it.
Information for this article was provided by Tina Potter, Utah Certified Nurseryman, Washington State Certified Nursery Professional (Lifetime), & Lawn & Garden Dept., Ogden IFA Country Store Brinn Hutcheon, Garden Center Asst. Manager, Riverton IFA Country Store and Kent Mickelsen, Utah Certified Nurseryman, IFA Agronomy.