Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding.

sap

A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit.

cane

This mite is one of the gall mites, also known as eriophyid mites. These are minute animals usually less than 0.2mm long when fully grown. They have elongate bodies and two pairs of legs, unlike other mites which have four pairs. Their size means they can usually only be seen with the aid of a microscope. For most species their presence is readily detected by the distinctive abnormal plant growths induced by their feeding activities. The red berry mite is unusual for these mites in that it doesn’t cause galling.

There are many species of eriophyid mite which are usually host specific this means that each species of mite will only feed on a single, or several closely related, plant species.

Eriophyid mites feed by sucking sap but while doing so secrete chemicals into the plant tissue that converts some of the normal (parenchyma) plant cells to

Meristem is a type of tissue that is responsible for growth and development in plants. It consists of unspecialised cells that can divide and diversify into various types of specialised cells. Meristems are only found in certain parts of a plant, such as at root and shoot tips and in bundles between xylem and phloem vessels.

Red berry mites overwinter under bud scales and become active on the foliage during the spring. When in bloom the mites move onto the flowers and developing fruits.

The first fruits to develop usually ripen fully but later fruits show increasingly patchy ripening, with some parts of the berries remaining hard and red or green. The patchy ripening is sometimes referred to as ‘red-berry’ disease.

There are no suitable controls available to home gardeners for the mite and so the damage has to be tolerated. Heavily affected canes can be cut to ground level as soon as the problem is noticed and disposed as diseased material. Consider replacing canes with persistent problems of red berry mite.

Partly ripened berries can be used for cooking, making jam or wine.