A review of common diseases of pineapple: the causal pathogens, disease symptoms, and available control measures

Pineapple is a perennial fruit-bearing tropical plant that belongs to the Bromeliaceae family, which has more than 2500 species. Pineapple is known excellent source of minerals and vitamins. It produces substantial calcium, potassium, glucose, the proteindigesting enzyme bromelain, fibre, vitamin A, B and C. In Malaysia, twelve registered varieties of pineapple have been introduced and commercially planted such as Moris (AC1), Sarawak (AC2), Gandul (AC3), Maspine (AC4), Josapine (AC5) Yankee (AC6) Moris Gajah (AC7), N36 (AC8), MD2 (AC9), View of Sunset (AC10), Madu Kaca (AC11), and Keningau Diamond (AC12). The disease is one of the important factors that can contribute to the huge losses of pineapple yield worldwide. This review paper aimed to discuss the main diseases of pineapple and their control management, particularly in Malaysia. The common diseases of pineapple that cause significant yield losses in the farms such as mealybug wilt-associated virus, bacterial heart rot, fruit collapse, butt rot, fruitlet core rot, black rot, yeasty and fusariosis are highlighted and discussed in detail on the causal pathogens, disease symptoms and signs, disease infection and development. The available control measures for managing pineapple diseases were also included in this paper.

Dysmicoccus neobrevipes (grey pineapple mealybug).

Dysmicoccus neobrevipes is a mealybug with a pantropical distribution. It is an economically important pest that can feed on and damage dozens of hosts, principally pineapple and the banana Musa × paradisiaca. The main damage caused by D. neobrevipes is due to its role as a vector of mealybug wilt (Plant Health Australia, 2013). Qin et al. (2010) considered it a dangerous alien species with a high risk of invasion in China. Although D. neobrevipes can colonize without the help of associated caretaker ants, most commonly Pheidole and Solenopsis, the ants' presence can help them to invade new areas by providing shelter and protecting them from natural enemies and adverse weather conditions.

Strategies for vegetative propagation and viral cleaning of a miniature ornamental pineapple hybrid

This study assessed and compared different methods for vegetative propagation of a miniature ornamental pineapple hybrid (ORN-MUT), seeking to determine the best method for production of plantlets, as well as for removal of the PMWaV viral complex from plants cultured in vitro, for production of healthy parent plants. Pineapple wilt is a disease that can cause large economic and is caused by a viral complex called Pineapple mealybug wilt-associated virus (PMWaV). For this, four propagation methods were evaluated (conventional, stem sectioning, micropropagation and etiolation of nodal segments). The time necessary for each method and the number of plants formed were assessed. Stem tips (0.5 mm) were cultured and indexed for three PMWaV types. Conventional propagation produced 17 plantlets per plant in 566 days, stem sectioning produced 2.3 plantlets per stem in 591 days, while the conventional micropropagation technique produced 1,284 plants after four subcultures in 778 days. Stems etiolated for 60 days showed peak production in the second subculture, with 1,224 plants. This method required 883 days to obtain plants with ideal size for transplantation to the field. In turn, stems etiolated for 120 days produced 935 plants at the end of four subcultures, with peak output in the third subculture, in which the plants could be cultivated in the field after 943 days. Conventional micropropagation and etiolation for 60 days were the best methods for production of plantlets of the ORN-MUT hybrid. The results of this work showed that the cultivation of shoot tips is an efficient strategy to remove the PMWaV complex and obtain healthy mother plants and can be a useful tool for other varieties of pineapple.

Prevalence of Dysmicoccus brevipes (Cockerell, 1893) (Hemiptera: Pseudococcidae) in MD2 pineapple crop areas in Colombia

ABSTRACT Pineapple mealybug wilt has been reported as one of the most important diseases affecting pineapple crops worldwide. This study aimed to determine the prevalence of mealybugs associated with two agroclimatic zones of pineapple production in the department of Valle del Cauca, Colombia. The survey was conducted in the upper (Dagua, Restrepo, La Cumbre and Vijes) and lower (Buga and Palmira) land zones. A total of 75 MD2 pineapple plots in different development growth stages were evaluated. The mealybugs were recorded mainly in the upper land zone, with a prevalence of 32 %. Concerning the plots growth stages, the highest prevalence was observed in second-cycle plots (13.3 %), followed by third-cycle ones, including abandoned plots (9.3 %), and first-cycle plots (6.7 %), which were associated with the use of pesticides. Dysmicoccus brevipes was the only mealybug species (Pseudococcidae) found on pineapples in the study area.

Bromelia pinguin (wild pineapple).

Bromelia pinguin is a large, perennial bromeliad with spikey fronds that grow up to two metres long. It often grows in dense colonies. It is native to the Neotropical Region but has been introduced as an ornamental to Florida, Hawaii and other Caribbean islands as well as India and Sri Lanka. Though some sources consider it native to Cuba, it is also recorded as invasive, where it is invading forests and savannahs, displacing native vegetation and providing a niche for small invasive mammals. It is also an alternative host to Pineapple mealybug wilt-associated virus 2 (PMWaV-2), which threatens commercial pineapple farming in Cuba.