93 



Near Vieux Habitants a small patch of 

 pnckly-pear (0. triacantha) was noticed to be 

 badly attacked by a fungus rel3,ted to and per- 

 haps identical with Gloeospormm lunatum, Ellis 

 and Ever., which produces an anthracnose dis- 

 ease or shot-hole " in 0. lindheimeri and other 

 species m Texas. Within the area, the plants 

 are very comanonly less than a foot in height 

 the majority being seedlings or young plants 

 which had risen from seeds or segments of plants 

 that had been killed by the parasite. The symp- 

 toms were similar to those described by Wolf 

 (1912 a, p. 124), and met with by the Commis- 

 sion during its investigations in Texas. In addi- 

 tion, the presence of shot-holes and erosions of 

 the edge of affected segments— the " black rot " 

 stage— was also evident; death of the attacked 

 joint being the result. It appears to be especi- 

 ally virulent at a certain period of the year 

 (rainy season), a fact already referred to by 

 Wolf in his account of the malady in Texas. 



The species of prickly-pear (0. triacantha) 

 victimised being strikingly different from any of 

 the commoner Australian naturalised prickly- 

 pears, it would not be surprising if the disease- 

 producing organism whose distinctness from 

 Glceosporium lunatum, Ellis and Ever., might be 

 physiological only, would prove wholly ineffective 

 in damaging any of them. . This is indeed sug- 

 gested by the observation that plants of 0. dil- 

 leim, a species more nearly related to our intro- 

 duced forms, although growing only a few feet 

 from affected plants of 0. triacantha, had re- 

 mained wholly unattacked by the malady so 

 prejudicial in this instance to the last-mentioned 

 species. 



ANTIGUA. 



This island of the Leeward Group, 108 square 

 miles in extent, is one of the drier of the West 

 Indies, and is generally favourable to the growth 

 of plants of the prickly-pear group. 



The investigations made there included a 

 plant survey of (1) each side of St. John's Har- 

 bour, on the west coast, and the country between 

 it and Five Islands Harbour, south therefrom; 

 (2) of the country adjacent to Falmouth and 

 English Harbours, on the south coast; and (3) 

 of Parham and Belfast Bay districts, on the 

 north-east coast. 



The species of prickly-pear encountered 

 were : — 



(1) 0. dUlenii, Haw. 



(2) Opuntia sp. allied to 0. dillenii. 



(3) 0. triacantha (Willd.), D.C. 



(4) 0. catacantha, Link and Otto. 



(5) Nopalea cochinelifera (L). 



Of these the second mentioned is identical 

 with the Opuntia already referred to as growing 

 commonly at Barbados, and the fourth is a plant 

 having very elongate stem-joints, and attaining 

 the dimensions of a small tree. Grisebach (1864, 

 p. 302) refers to two of them as being known to 

 him as Antiguan plants, viz.. No. 1, that he names 

 0. tuna, and No. 3, that he correctly designates 

 as above. 



0. dillenii was found to be the most pre- 

 valent species, and although — as was the case 

 of one or more of the other kinds — often absent 

 where it might be expected to occur, was some- 



times met with in fairly dense masses, especially 

 where unaffected by disease and favoured by 

 soil-conditions. Its orange-flowered ally com- 

 monly occurred growing with it, but was com- 

 paratively rare in the Parham and Belfast Bay 

 districts. Both it and 0. dillenii had been used 

 extensively as a hedge plant. 0. triacantha 

 often formed large, impenetrable, low patches 

 adjacent to Falmouth and English Harbours, 

 and was said to be spreading. 0. catacantha was 

 noticed on ridges and in rock-faces at the eastern 

 end of the island. 



Disease Occurrence. 

 (1.) Wild Cochineal Insect {Dactylopius 

 confusus newsteadi, Ckll.) : — It had been re- 

 corded that a special kind of wild cochineal insect 

 was to be met with on prickly-pear at Antigua, 

 but it appeared to be rare, having been found 

 only on a single plant here in 1901; Mr. Ballon, 

 the Entomologist of the Imperial Department of 

 Agriculture, stating that he had not succeeded 

 in rediscovering it. Again, Mr. T. Jackson, the 

 Curator of the Botanic and Agricultural Ex- 

 periment Stations, had not seen this natural 

 enemy, although conversant with the Opiintia- 

 infested areas of the island. However, in the 

 small village on the south side of St. John's 

 Harbour, adjoining the capital, N. cochinelifera, 

 which occurs there either as a hedge plant or as 

 a garden-escapee, is, in many instances, so white 

 by reason of the presence of the insect that its 

 abnormal appearance is discernible for a con- 

 siderable distance. On nearer approach the en- 

 tire surface of the infested plants was found to 

 be covered with a flour-like dust, and large con- 

 spicuous whitish patches of the insects themselves, 

 congregated together, were seen on many of their 

 stem-joints. Their presence was attended with 

 little or no injury to the host-plant, a superficial 

 brown discolouration being sometimes discernible 

 when the parasite was removed from the spot 

 where it had been feeding. 



Two other species of prickly-pear (0. dil- 

 lenii and its gilvous-flowered ally, Opuntia sp.) 

 grew commonly near where the plants of the 

 species favoured by it occurred, but as far as 

 could be observed they had wholly escaped in- 

 festation by it. 



(2.) Anthracnose or Shot-hole Disease 

 {Glceosporium lunatum, Ellis and Ever.). — In 

 the same locality plants of the gilvous-flowered 

 prickly-pear {Opuntia sp.) were seen to exhibit 

 the chaarcteristic injury attendant on the pre- 

 sence of this disease. The malady was, however, 

 in a non-active condition at the time of the 

 inquiry and was restricted to one or two plants 

 only, and even these it had but little checked 

 in their growth. Injuries of old standing else- 

 where on the prickly-pear plants suggested that 

 during certain seasons of the year the disease 

 might be more marked. 



What appeared to be a similar disease, if not 

 one originally of bacterial origin, was pointed 

 out by Mr. Jackson as causing considerable in- 

 jury to a plant of 0. rohusta, growing in the 

 Antigua Botanic Gardens under his management. 



(3.) Zone Spot Disease. — This disease was 

 found exclusively associated with 0. dillenii, 

 Haw., and was remarked also in the neighbour- 



