Aloe Die-back in Gibraltar

A few years ago a disease was proliferating among the Tree Aloes, Aloe arborescens around Gibraltar.  Large stands of the plant around Europa Point and the east side of Gibraltar were badly affected, and several stands were unable to survive, and perished.  Those that did weather the storm, recovered slowly during the winter months and managed to put on the display of their colourful and characteristic flowers; the red pokers.

The Tree Aloe is not native to Gibraltar, and was shipped over from South Africa and  introduced into gardens in the 19th century, mainly in the south District, where officers had their quarters.  It is an alien species, but not invasive, and the species does not set viable seeds.  It propagates mainly through their root systems, and grows rather slowly, making a recovery extremely difficult.

Diseased Tree Aloe
                            Diseased Tree Aloe with browning of the leaves.
Diseased Tree Aloe
               Diseased Tree Aloe, most of the leaves are affected except the centre growth.
Diseased Tree Aloe
      Diseased Tree Aloe; the black specks are the faeces of the Thrip insect.

The disease, which has not been identified, may be fungal or bacterial, and is spread by an insect, a species of Thrip that is feeding on the sap of plant, breaking through the hard skin and thereby introducing the pathogen within the plant.  The Thrip is microscopic, less than half a millimetre in length.

 

Aloe Thrip
                  Aloe Thrip, the vector of the disease of the Tree Aloe.

This year, the disease is back, strongly affecting those few stands which survived.  It shows as a browning of the lower leaves , with brown rust coloured spots quickly spreading and drying the leaves, and covered in small black sploshes, which are the faecal matter of the insects that are sucking the sap.  Eventually the last few leaves growing at the head of the stem dries out and the plant dies.

 

 

Macaque Outing

Macaque Outing

The next GONHS outing will be held on the 18th November at 09:30 at the Apes' Den.  Non-members are welcome but we ask for a donation of £5 to be made.

Read more

Birds Ringed at the Observatory

Birds Ringed at the Observatory

Here is a gallery of some of the rare and more unusual birds that have been trapped and ringed at the Observatory this autumn.

Read more

Autumn flowers

Autumn flowers

There are some characteristic plants that begin to flower in the autumn, with some already present and others beginning to flower now.

Read more

EuroBirdwatch 2017 (part 2)

EuroBirdwatch 2017 (part 2)

The second part of EuroBirdwatch took place on Saturday 7th October during the morning.  Ringer in residence, Ray Marsh, was at the event ringing birds caught at the Gibraltar Botanic Gardens to show to members of the public.

Read more

Why is the Wryneck so called?

Why is the Wryneck so called?

The Wryneck gets its name from the ability to turn its head from side to side and back and forth in the manner of a snake.  This ability is thought to imitate a snake, to deter predators from their nest.  They will also assume this habit when held in the hand.  See our video

Read more

International Bat Night 2017

International Bat Night 2017

The 10th edition of the International Bat Night under the auspices of Eurobats / BatLife Europe was held on Friday 6th October 2017 at the Open Air Theatre at the Gibraltar Botanic Gardens.

Read more

EuroBirdwatch 2017

EuroBirdwatch 2017

The first leg of our EuroBirdwatch 2017 events took place on Sunday 1st October at Europa Point. 

Read more

Iberian Chiffchaffs on passage

Iberian Chiffchaffs on passage

Iberian Chiffchaffs Phylloscopus ibericus are now passing through the area of the Straits on their way to their winter quarters in Africa.

Read more

Join Us

Under 18's

Under 18's

£10

Adults

Adults

£25

Family

Family

£35

Business

Business

£500

Donation

Donation

£--

  • UKOTCF
  • Bat Life Europe Logo
  • BTO Logo
  • Bird Life International Logo
  • IUCN Member Logo
  • University Of Gibraltar Logo