Why have your runner beans got small yellow leaves?

* Nutrient deficiency. Runner beans need a lot of nitrogen, potassium, and phosphorus to grow well. If your soil is deficient in any of these nutrients, it can cause the leaves to turn yellow.

* Over-watering. Runner beans don't like to be waterlogged. If the soil is too wet, it can cause the roots to rot and the leaves to turn yellow.

* Under-watering. Runner beans also don't like to be dry. If the soil is too dry, it can cause the leaves to wilt and turn yellow.

* Disease. There are a number of diseases that can affect runner beans, including rust, powdery mildew, and bacterial wilt. These diseases can cause the leaves to turn yellow and drop off the plant.

* Pests. Pests, such as aphids, spider mites, and whiteflies, can also cause runner bean leaves to turn yellow. These pests can suck the sap out of the leaves, causing them to turn yellow and drop off the plant.

Solutions

If the leaves on your runner beans are turning yellow, there are a few things you can do to try to fix the problem:

* Test your soil. If you think your soil might be deficient in nutrients, you can have it tested by a soil testing lab. This will tell you what nutrients are missing and how much you need to add to the soil.

* Water your runner beans regularly. Runner beans need about 1 inch of water per week. Water them more often if the weather is hot and dry or if the soil is sandy. Avoid over-watering, as this can cause the leaves to turn yellow.

* Avoid waterlogging. Runner beans don't like to be waterlogged. If the soil is too wet, it can cause the roots to rot and the leaves to turn yellow.

* Control pests and diseases. If you see pests or diseases on your runner beans, take steps to control them. You can use a variety of methods to control pests and diseases, such as pesticides, fungicides, and neem oil.