Garden Tool Set

Symptoms: The small red galls, shown in the photo to the left. They appear on the upper surface of the leaf.

Cause: Aceria cephaloneus mites suck the sap in the leaf, which induces the plant to react with the galls.

Control: There is no need to control this issue for the plant, as there is no harmful effect on the host. For small infestations the leaves can be removed, which will improve the look of the plant.

Symptoms: The galls are around 5mm long as seen in the photographs and begin from late spring onwards. This occurs on the leaves of Lime trees, such as Common Lime.

Cause: is due to the chemicals secreted  while feeding on the underside of the leaf by a gall mite that is microscopic and goes by the name of Eriophyes tiliae. The galls are hollow and the mite lives within them during the summer.

Control: The mites don't have any harmful effects on the tree other than creating the galls. They can therefore be tolerated. In some ways, I find them quite interesting and exotic - however, I can see that some may not!

Symptoms: Develops on the catkins and leaves of both pedunculate and sessile oak trees. There seem to be two stages, with the galls in the photographs being one stage and the spangle galls being another.

Cause: Caused by a small gall wasp.

Control: There doesn't appear to be much stress on the tree, so can be left in place. Also there can be many galls on each tree, making it very difficult to keep under control.
Thanks to OllieBeak at WAB for the help in IDing this gall. I found an ID guide from the NHM, available here as a PDF.

Symptoms: Develops on the underside of the leaves of pedunculate oak (Quercus robur) and sessile oak (Quercus petraea). The discs begin as yellow-green and age to become reddish.

Cause: Caused by a small gall wasp called Neuroterus quercusbaccarum. These galls are created when the wasps of the currant gall generation emerge and lay their eggs on the underside of the leaves. The offspring of these eggs will emerge around April and the cycle will begin again.

Control: There doesn't appear to be much stress on the tree, so can be left in place. Also there can be many galls on each tree, making it very difficult to keep under control.

Symptoms: Young leaves breaking from buds which were infected during the previous year will show symptoms. Leaves are covered with a white growth.

Cause: This is caused by the fungus Podosphaera leucotricha. It overwinters in apple buds or on young stem growth - which can be seen as silvery white patches on the bark.

Control: Keep the plants well watered to prevent development. Mulch to preseve soil moisture. Prune out severely affected stems. Ensure the tree is pruned to ensure good air circulation.

Symptoms: A hard, woody-like structure on the twigs of Oak trees. These often appear in clusters.

Cause: Caused by a small gall wasp.

Control: There are no chemical control methods for the Oak marble gall. There doesn't appear to be much stress on the tree, so can be left.

Symptoms: Black spots on leaves. They can be seperate or enlarge and join together. As seen in the photo, the leaves can turn yellow. They can also fall prematurely.

Cause: This is caused by the fugus Diplocarpon rosae. This seems to overwinter in the lesions on stems, bud scales and on fallen leaves.

Control: Dispose of infected leaves promptly. During spring prune out stems with lesions. Fungicide treatment is available, but if the infection isn't too bad then the plant isn't affected too much.

Symptoms: Damage to the spinach leaf as the larvae mine through the leaves creating a blister. The epidermis has been removed from one side of the leaf, in the top photo, to reveal the leaf miner.

Cause: Caused by a the spinach leaf miner. The fly emerges in spring, mates and lays eggs on the spinach leaves (as below). They eventually drop from the leaves into the soil to pupate - creating the next generation. There can be several generations each year.

Control: Stop the adults reaching the spinach by using covers. Keep the area weed-free. Rotate spinach, chard, and beet crops. Try using a Neem based spray which acts as a repellant and also slows the leafminers' ability to feed, interrupting the cycle. Advice on making neem spray can be found here - I don't know of its effectiveness.

Symptoms: The gall wasp (Andricus quercuscalicis) convert acorns into ridged structures. This process begins around September and the yellow-green galls age over time to become brown and drop off the tree.

Cause: Caused by a small gall wasp, which lays a single egg in each gall. This is a two-part process with the sexual generation developing galls on the catkins of the Turkey Oak in spring.

Control: While there were initial fears that this would impact the ability of the tree to reproduce, there doesn't seem to be any real issues and treatment is not required.

Mistletoe

Parasitic plants can get a bad name for themselves, in fact some of the most detested 'parasites' aren't parasites at all.

Take, for instance, ivy. Ivy often has a bad name because people thing that it's parasitic on trees and can kill them. Ivy isn't parasitic as it can photosynthesize and has it's feeding roots, that provide nutrients and water, in the ground. However, ivy does throw out 'roots' that provide the superglue-like adhesive that allow it to stick to the tree - or house! - to get it to a height where it can change from juvenile to adult. So it can be easy to make this mistake.

True parasites are either Holoparasites or Hemiparasites: 

• Hemiparasites contain little or no chlorophyll and therefore cannot photosynthesise. They reply completely on the host plant for nutrients, fixed carbon and water.  

• Hemiparasites can photosynthesise and therefore normally just rely on the host for water and nutrients.

They attach to their host either at the host's stem or root.

The parasitic mistletoe is a classic hemiparasite that attaches via the stem. In the UK mistletoes are now being encouraged due to worries that they may disappear from our landscape in the near future. They are commonly grown on trees in orchards, like the example below that was photographed at The Courts Gardens in Holt that is run by the National Trust. As mistletoe doesn't require too many resources, the tree isn't badly affected by the presence of the mistletoe and will do just fine.


Here's another example of mistletoe, this time in The Netherlands. Mistletoe seems much more common there than here - and is obviously abundant in the photo above. I have visited this part of The Netherlands over the past 28 years and always remember the balls of mistletoe in the area, which is testament to the ability of the trees to cope with this sort of parasite.













To the left is the hemiparasite, the purple toothwort. As you can see it has no leaves or other green parts and therefore has no chlorophyll to photosynthesise with and relies on the perennials that it parasitises, including trees, via their roots to survive.














Another example of a hemiparasite is the common broomrape. However, which this parasite attaches to the root of host plants, it parasitises plants similar in size to itself. While purple toothwort attaches to perennials such as trees, the common broomrape attaches itself to the roots of clover.
One can only imagine how many attachments it requires to nearby clover plants to throw up these impressive flower spikes.










It's easy to see why parasitism is an attractive way of live, in fact there are around 4000 species of parasitic plants identified to date. However if the parasite puts too much of a drain on the host, then when the host dies, it may die too. To combat this, root parasites can attach to the roots of many plants and will only be affected when wider environmental aspects come into play.

Symptoms: As in the photo to the left, white froth appears on the leaves, stem or flowers of many plants - here on lavender. This happens around early summer.

Cause: This is caused by the immature nymph stage of froghoppers. The froth protects and provides moisture of the immature nymphs. From mid-summer onwards they reach adult form and the froth will become less noticeable. More information on froghoppers here.

Control: Control is not normally necessary as the cuckoo spit is temporary and the plant can normally handle the amount of sap lost to the immature nymphs. If the nymphs are feeding at the tips of the plant, then remove by hand or accept that come distorted growth may occur.


One of the reasons that I like this blog is because of the readers. Lucy commented below about brushing aside the 'spit' to reveal the nymph. Naturally I had to rush out and do this. I was surprised at the size of it, nearly a centimetre long and brilliant green. Here's a photo. Thanks to Lucy - to visit her fab blog click here.