Seasonal population of the fruit-piercing moths Eudocima spp. was monitored throughout the citrus growing seasons in a citrus orchard and in site adjacent to secondary forest from July 2007 to June 2009. The moth was detected practically throughout the year with activity lowest during the wet months (September-February) when fruits are still available and while highest during the dry months (May-June) which also coincided with the main fruiting season. The effects of an nC24 horticultural mineral oil (HMO) on the citrus fruit damage caused by fruit-piecing moths was also determined. The percent fruit damage was significantly lowest (P≤0.05) in HMO-treated plots (8.4), followed by Dimethoate-treated plots (11.6) and untreated plots (22.5). However, there was no significant difference between HMO and Dimethoate treated plots indicating HMO is effective in reducing percent fruit damage.
Most tropical rainforest tree species depends on forest gaps for their successful
regeneration. Evaluation on the gap or canopy openness provides an indicator on the
forest development stages. This paper reported on the canopy openness (CO) of three
study plots at (1-, 9-, 18-year old) rehabilitated forest sites and one study plot at natural
regenerating secondary forest (± 22-year old) in UPM-Mitsubishi Corporation Forest
Rehabilitation Project, Universiti Putra Malaysia Bintulu Sarawak Campus (UPMKB).
Plot of 20 x 20 m was established where dendrometric parameters were collected
while Delta-T Device HemiView system was used to take the hemispherical photograph
and field observation information were used to assess the CO. Qualitative analysis of
the photographs suggested there were three stages of forest growth namely gap,
building and mature stand development phases. These also helped the interpretation
of the quantitative analysis in relation to forest dynamics. Hemispherical photographs
were used for quantitative analysis of the CO. CO showed statistical significant
differences among study plots which recorded a range of 3-78%. Rapid analysis of CO
on the hemispherical photographs with information from the dendrometric
measurement had assisted in assessing the forest stand development. The canopy
openness was dependent on the age of the rehabilitated forest. Overall, the study plots
were in the different stages of stand development.
Aspects of the incidence and spread of the citrus disease huanglongbing (HLB) in relation to the vector Diaphorina citri population fluctuation were studied from January 1999 to December 2001 seasons in a 0.8 ha citrus orchard at Jemukan (1° 33'N, 110° 41'E), Southwest Sarawak in Malaysia. In relation to insecticide and horticultural mineral oils (HMOs) use, levels of HLB infection rose quite rapidly over the next 3 years in the unsprayed control and less rapidly in the other treatments such as imidacloprid, nC24HMO, and triazophos/cypermethrin/chlorpyrifos. Levels of HLB as determined by Polymerase Chain Reaction (PCR) were 42.2%, 9.4%, 11.4%, and 22.7%, respectively. The effects of nC(24)HMO and conventional pesticides on the citrus psyllid population and parasitoids in citrus orchard were also determined.