Beans are a delicious and healthy addition to any garden. However, many gardeners find that their beans aren’t doing as well as they should or have stopped producing altogether.
Here are 16 reasons why your beans might be dying:
- Insect infestation
- Slugs and snails
- Root maggots
- Blossom drop
- Crown gall disease
- Damping off disease
- Anthracnose fungal disease
- Root-knot nematode disease
- Fusarium wilt disease
- Not getting the right nutrients
- Poor soil temperature
- Poor soil drainage
- Too much fertilizer
- Seedlings not emerging from the soil
- White or gray mold
There can be several reasons why your bean flowers will not set pods. Below is everything you need to know about why your beans may be dying and what you can do to protect them.
1. Insect Infestation
Bean plants are an all-you-can-eat buffet for many different pests.
The following are some of the most common garden pests that will feed on bean plants:
Aphids are tiny green, gray, or black insects that will swarm over your plants and suck the life out of the flowers. They are some of the most common garden pests, and they are tricky to get rid of since they are so small and reproduce so quickly. They also spread diseases to your plants and carry infections with them as they snack on the sap in your garden veggies and beans.
Beyond common aphids, some aphids are attracted explicitly to beans. This insect resembles common aphids, but they attack soybeans instead of beans. Beans with these aphids usually develop yellow or bronze spots, and this discoloration spreads as the insect feeds.
To get rid of a small outbreak of aphids, give them a spray from the garden hose. You should then apply insecticidal soap twice, over two weeks. Make sure to cover the beans, including the underside of the leaves.
Thrips are tiny insects that also feast on plant leaves, stems, and flowers. They “skeletonize” the foliage by attacking only the leaf material between veins. Thrips will go after beans just as soon as they start emerging.
To deal with thrips, you should use sticky pest traps if you’re dealing with a minor outbreak. A large infestation will require pyrethrin (or similar) insecticide spray. Oil-based sprays are best for smothering thrips and poisoning them.
Bean plants are susceptible to two different beetles that will eat the foliage.
The Mexican bean beetle is grayish-green with a row of white spots down its back and several black spots on each side. Adults lay yellow eggs, which hatch into tiny, red larvae with black heads. The larvae are usually found right at the bottom or top of the plant.
The other type is the false Japanese beetle. This olive-brown beetle has three ridges along its back with eight projections in between them. Unfortunately, larvae can cause more damage than adults because they have chewing mouthparts they use to skeletonize leaves and chew holes in the pods.
When dealing with a small number of bean beetles or using an insecticidal soap and drenching the stems and leaves of your bean plants are the best way to go.
Bean weevils are black beetles that are about the size of a ladybug. Bean weevils have grooves along their back and three large bumps on each side.
These beetles feed on flowers and foliage daily and chew small holes in pods at night. They also lay eggs in bean pods that hatch into larvae. From there, the larvae eat the pod to escape from it.
Prevention is the only way of dealing with bean weevils as no chemicals can be used against them. You’ll need to follow the proper preparation advice for growing beans, which we’ll discuss more in a later section.
Also known as potato beetles, flea beetles are tiny, dark-colored beetles will chew hundreds of little holes in leaves and flowers. The larvae are puny and only grow to about 1/4-inch (0.63-cm) long. Still, they can cause significant damage, especially if they kill your beans before they flower.
Using sticky traps is a great way to capture flea beetles as they try to jump. Alternatively, a dash of talcum powder dusted over your plants can help to repel these pesky insects.
One of the more common problems for gardeners, cutworms are caterpillars that chew the stems and roots of bean plants off below ground level.
If you notice that your bean plants are suddenly wilting, digging up the ground at this point is likely to reveal a cutworm. Sometimes, you’ll find them curled upright on top of the soil.
To get rid of cutworms, try sprinkling moist bran mixed with Bacillus thuringiensis kurstaki or Btk (a bacterial toxin) over the soil surface around your beans. Btk is usually safe for vegetables and flowers, but it completely paralyzes worms when applied correctly.
2. Slugs and Snails
Slugs and snails are two of the most common pests in the garden and can cause severe damage to your plants. They feed on leaves, flowers, and fruit and quickly eat through a bean plant.
One way to help protect your plants is to place a copper strip around the garden’s edge or use beer traps to attract them. You can also handpick them off plants or use organic slug bait (safe for pets and wildlife).
You can tell if you have a caterpillar problem by looking at your plants. If there is evidence of larvae feeding on plant leaves and fruit, you must take fast action.
Spraying plants with Btk or using an insecticidal soap spray can help deal with minor infestations, but sometimes this just isn’t enough. Handpicking caterpillars off the plants and destroying them, and not leaving overripe fruit lying around are great ways to discourage these pests from returning.
4. Root Maggots
Root maggots are tiny white grubs that feed on bean roots, which hampers the plants’ ability to draw water and nutrients through their root systems. You’ll typically find symptoms of root maggots in bean plants that produce poorly and wilt quickly.
One of the best ways to stop root maggot problems is crop rotation. Planting marigolds around the perimeter of your garden is another excellent way to keep them away. When broken, they will release a substance called pyrethrum that discourages maggots from setting up camp on your turf.
General Advice for Eradicating Insects & Pests
As you can see, several different pests will feed on your beans and cause them to die. The best way to prevent these insects is through prevention.
Here are some helpful tips for preventing pests in your garden:
Use Organic Pest Control Measures
Planting marigolds around the perimeter of your garden or using diatomaceous earth will help keep many common insects away. Insecticidal soap (or natural pyrethrin) sprays work great for getting rid of minor infestations, and oil-based sprays work well for more significant outbreaks.
Bean Seedlings Placement
When planting seedlings, make sure you place them about 12 inches (30 cm) apart. Apply a new layer of mulch about one-inch (2.54 cm) deep and some diatomaceous earth on top of that.
The mulch will help keep the soil from getting too hot, and the diatomaceous earth will help keep crawling insects from entering your garden.
Practice Proper Rotations
Beans belong to a family of legumes, so they work great in a rotation with other vegetables such as cabbage, corn, cucumbers, and potatoes. These vegetables all have different growing requirements, so rotating them keeps soil nutrient levels balanced while reducing pest pressure.
Clear the Area of Weeds Before Planting
Weeds can harbor insect larvae and worms that will move on to feed on your beans. When you pull weeds, make sure you dispose of them promptly since weed piles may serve as an insect breeding ground.
Spread Mulch Around Plants
Keeping the soil covered with a thick layer of mulch (2 inches or 5 cm or more) can help prevent some pests from laying eggs on the soil surface. It also helps to maintain soil moisture levels throughout the growing season.
5. Blossom Drop
One of the most common reasons for bean plant failure is end blossom drop. This process occurs when the buds at the ends of branches won’t open into flowers.
If they do open, they don’t produce any pods. Blossom drop is a regular occurrence very early in the season, but it should cause concern after that.
The cause of this could be lack of pollination, extreme temperatures during pollination, high winds which shake the flower off the bud, worms eating the flower, poor pollination conditions, or a lack of water or nutrients.
You can prevent and treat blossom drop using a flower set spray specially made for beans. Typically, this spray is marketed as tomato set spray, but it works on various plants, including beans.
You can improve the pollination process by placing more beehives in the area or adding fragrant flowers to your garden. Bees and other pollinators are responsible for 75% of plant pollination, so increasing their presence can positively affect your bean plants.
6. Crown Gall Disease
Crown gall disease is a bacterial infection that affects the crown and roots of a bean plant. It can cause the plant to wilt and die.
The gall is a tumor-like growth caused by bacteria. The growth can block the flow of water and nutrients to the plant, leading to its death.
Crown gall disease is most commonly spread through contact with other infected plants or soil. Insects like aphids and nematodes can also spread it.
There is no cure for crown gall disease, but you can prevent it by using resistant bean varieties, destroying infected plants, and practicing proper sanitation practices.
7. Damping Off Disease
Another common problem with bean plants is damping off. This process occurs when your seedlings grow rapidly but suddenly fall over and die.
The soil at the base of the stem will be soft and wet, often covered in a white or brown fungus. This disease can be pretty damaging to legumes, particularly mung beans.
The leading causes of this disease are:
- Poor air circulation
- Too much moisture around your bean plant’s roots
- Overcrowding due to high seeding rates
You can prevent it by carefully spacing out your seedlings to have plenty of space between them. Be sure to expose the soil surface around your seedlings to some direct sunlight once they sprout through the ground. Also, you should remove any plant debris at the end of the season.
8. Anthracnose Fungal Disease
The anthracnose fungus causes lesions in the leaves of bean plants that will turn brown and fall off. This disease can sometimes prevent flowers from forming, causing beans to drop before they mature.
The spores of this disease are carried by wind or rain and are only possible during cool and wet conditions. They also spread through infected plant debris on garden tools or soil.
Another way this disease can spread is by planting an already infected seed. Make sure to buy your seeds from reputable sellers, as the infection will likely spread once planted.
Prevention is best done by:
- Using resistant bean varieties
- Rotating crops often with non-legume plants
- Avoiding overhead watering practices
- Destroying any infected plant material at the end of the season
- Carefully cleaning any gardening equipment after working with your beans, so no trace amounts remain
9. Root-Knot Nematode Disease
Another common problem for legumes is root-knot nematode or Meloidogyne spp. These tiny microscopic organisms enter the roots of your bean plant and cause immense damage.
The root system will often be deformed, turning into knot-like structures that inhibit the plant’s flow of water and nutrients. This can lead to yellowing leaves and wilting, resulting in death if left untreated.
The only way to diagnose this disease is by having your soil tested for root-knot nematodes through a lab service.
Prevention for this includes:
- Planting resistant varieties
- Avoiding dense planting where excessive competition occurs
- Rotating crops with non-legume species
- Plowing your soil in between crop rotations to expose eggs in the ground to the sun’s heat, where they die off within a few weeks
- Avoiding planting beans in the same area for at least 3 to 4 years
10. Fusarium Wilt Disease
Fusarium wilt disease is a severe fungal disease caused by the Fusarium oxysporum f. sp. phaseoli, a soil-borne fungus that causes the vascular system of the plant to deteriorate.
This disease leads to wilting and discoloration in both leaves and pods, browning at the tips of young leaves, and occasionally yellowing foliage with a distinctive yellowing effect beginning on one side of the leaf. The roots will also turn brown and begin to rot.
Usually, this disease is more prevalent in areas with moderate climates during long periods of wet soil conditions. Most of the time, it spreads through infected seeds.
It’s best to buy your seeds only from reputable sellers since fusarium wilt cannot be cured once contracted by the bean plant.
The best way to prevent Fusarium wilt disease is by sterilizing the soil and ensuring you never plant beans too close together. Crop rotation is a great way to stop the disease from affecting your beans.
11. Not Getting the Right Nutrients
This problem is often related to the pH of your soil because beans need acidic soil (pH 5.5-6.8) to thrive.
Many gardeners don’t know that nutrients also become unavailable as the pH changes. This causes their plants not to grow properly or develop pods, blossoms, or seeds, which leads to no beans come harvest season.
Soil with high phosphate levels can make soluble phosphate unavailable for use by legumes like beans, so it’s best to spread phosphorus for fertilizers on your soil before planting your bean seedlings.
12. Poor Soil Temperature
Beans are sensitive to soil temperature, so they will become stunted or may not even germinate at all if you plant them too early.
You can improve their chances of success by planting seeds indoors in moist potting soil 4-6 weeks before the last frost date for your area. Then, transplant them into their final garden location when the first two sets of true leaves have formed on your seedlings after hardening off.
If you plant your beans at the proper time, they still face another potential problem due to high soil temperatures.
This issue happens because high soil temperatures during flowering times cause fertilization issues, resulting in no pod formation, spotty or non-existent blossoms, and deformed, malformed, or shriveled beans.
Soil temperatures between 60 and 80 °F (15.6 and 26.7 °C) are ideal for the germination and growth of pole beans. Still, if the soil becomes too hot (above 90 °F or 32 °C), this can kill them or inhibit overall growth.
13. Poor Soil Drainage
Beans generally prefer moist but well-drained soils that are rich in organic matter. The ground should become evenly moist when you water your plants, but if it becomes too wet or stays soggy, this can cause their roots to suffocate, which leads to stunted growth, yellowing leaves, and possibly death.
Poor soil drainage is also a severe problem for bean pods because they swell as they grow with too much moisture, which causes splits on the sides of the pod skins.
If the soil doesn’t drain appropriately after heavy rains or irrigation, this excess moisture will collect at the bottom of the plant’s roots rather than dissipating upwards through the plant tissue. This puddling and pooling can lead to rotting roots and blackened beans.
If your bean plants stay too wet, they won’t develop beans in their pods, and they’ll also exhibit symptoms like poor growth and deformed blossoms.
14. Too Much Fertilizer
Beans draw up nutrients from the soil through their roots, and since they are heavy feeders, it’s essential to make sure they get what they need. Beans absorb nitrogen from the air, so using too much fertilizer won’t benefit them.
Overfertilized beans become stunted or don’t produce pods or blossoms at all. That’s because this nutrient plays a crucial role in vegetative growth, which can affect flowering rates.
If you have added fertilizer to your bean bed before planting them, use a formula with low nitrogen levels, so there isn’t too much available during the early stages of growth when flowers form on the plant.
15. Seedlings Not Emerging From Soil
Beans should start emerging from the soil after about a week of consistent soil temps between 50 and 75 °F (10 and 23.9 °C). They can take around 2-4 weeks to germinate, depending on whether you planted them indoors or outdoors and their variety.
If your seedlings aren’t starting to peek out of the ground from their planting site, it can be due to low moisture levels, so water daily until the first leaves have formed.
It’s also helpful to create a small hill or ridge with loose soil next to each plant, so they have an incline as soon as they emerge from the ground, making for more manageable seedling growth.
Once plants have developed two true leaves, beans should grow quickly and produce blossoms within 2 to 3 weeks. If your plants look healthy at this point, but you still haven’t seen any pods or blossoms, this can be due to high maturation rates.
16. White or Gray Mold
White and gray mold grows due to excess watering, leading to fungus infection, particularly after heavy rain or irrigation periods. This mold isn’t exclusive to beans and can affect other plants in your garden, so it’s best to practice natural prevention for this issue promptly.
If you notice the presence of white or gray mold growth on any part of the plant, it’s essential to remove all affected leaves right away before the infection spreads even further along veins and stems. Pruning out affected areas will help curb its progress, but there are ways to address it in the early stages, too.
If water is pooling at the base of your bean plants when you go out into your garden, that could cause them to develop mold underneath ground level rather than above ground, where everyone else’s plants look healthy and vibrant.
You can ward off the mold by simply driving stakes next to the plants and attaching a drip line above them so that water doesn’t pool underneath.
If your beans aren’t growing well, it’s best to diagnose the problem right away and fix it before plants start to wilt. Probable causes of bean plant deaths include pests, infections, overwatering, improper fertilization, and improper temperatures.
Beans grow quickly and can be harvested within two to three months, depending on whether you’ve planted them as a summer crop or a fall one. So, make sure they have everything they need to grow healthy and robust by checking for any nutrient deficiencies before planting.