Weeds of upland crops in Cambodia
A weed identification guide for farmers and extension workers in the upland cropping systems of Cambodia. Sponsored by the Australian Centre for International Agricultural Research, the NSW Department of Primary Industries, and the Cambodian Agricultural Research and Development Institute. This book is part of a series of publications produced by ACIAR in support of the on-going rollout of on-farm demonstrations for upland crops in Cambodia.
Weeds of Upland Crops in Cambodia
The purpose of this book is to help extension workers and farmers to identify plants that are weeds or are considered to have the potential to become weeds in the upland cropping systems of Cambodia. Not all of the plants included are currently regarded as weeds, and many of them have useful purposes. However, with changing agricultural practices such as reduced or zero tillage, plant species currently controlled by ploughing could become weeds. These include perennial species and those with underground stems and rhizomes. Some important species known to be weeds of upland crops have not been included in this volume because of our inability to identify them or to obtain suitable photographic images. These will be included in a future revised edition.
Insects of upland crops in Cambodia
Crops are subject to attack from a wide range of insect species in the wet tropical environment of Cambodia, resulting in extensive damage and economic losses. This illustrated field guide will assist with the identification of the major insect pests of the main upland crops in Cambodia - cowpea, maize, mung bean, peanut, sesame and soybean. However, not all insects found in the crops are pests; some insects and spiders play a significant role in keeping the insect pests under control. The guide provides a brief description of insect pests and the damage they cause, as well as information on a range of beneficial insects and spiders that can be found in upland crops in Cambodia. The impact of beneficial insects can be increased by integrated pest management and careful use of pesticides.
Influence of Temperature and Humidity Regimes on the Developmental Stages of Green Vegetable Bug, 'Nezara viridula' (L.) (Hemiptera: Pentatomidae) From Inland and Coastal Populations in Australia
Laboratory studies were conducted to assess impacts of temperature and humidity regimes on the development of Nezara viridula (L.) (Hemiptera: Pentatomidae) from inland and coastal populations in NSW, Australia. Four temperature regimes, 25±2ºC, 30±2ºC, 33±2ºC, and 36±2ºC and two humidity regimes, 40±10% and 80±10% RH were applied in the experiment with a constant photoperiod of 14:10 h (L:D). The developmental time of the nymphal stage of N. viridula significantly decreased with increasing temperature. Percentage nymphal survival significantly decreased with increasing temperature or high humidity (80% RH) regimes. Longevity of N. viridula adults declined with increasing temperature or high humidity regimes and female longevity was longer than males. High temperatures (30, 33 and 36ºC) or high humidity significantly reduced reproductive performance and capacity of N. viridula compared to low temperature (25ºC) or low humidity (40% RH). However, high humidity significantly increased egg hatchability of N. viridula compared with a low humidity regime. Interactions of temperature and humidity regimes significantly changed incubation period, adult longevity, mating frequency, pre-mating period, egg-mass size and egg hatchability of N. viridula. Interactions of population location (coastal or inland), temperature and humidity regimes significantly changed incubation period and pre-oviposition period of N. viridula. Temperature and humidity are important environmental factors for the development and reproduction of N. viridula. Higher temperatures shorten the length of nymphal duration, but reduce nymphal survival. The optimum temperature for the development and reproduction of N. viridula was 25ºC with 40 ± 10% RH. No differences in nymphal duration, nymphal survival, adult longevity or reproduction performance between inland and coastal N. viridula populations were found under different climate conditions. We show the importance of assessing all life-stages in the response to varying temperature and humidity regimes, especially in terms of assessing responses to climate change.
Farmer's Challenge In Improving Upland Farming Systems in Cambodia
In upland areas during the rainy season, farmers generally attempt to grow several upland crops including maize, sesame, mungbean, soybean, peanut and cowpea. The first is planted in March-April and the second in July-August. Farmer workshops have provided us with a better understanding of traditional practices and problems associated with growing and marketing upland crops in Cambodia. The most commonly given reason for growing a crop is good market demand. High price for the product and ease of production are of equal importance. Low cost of seeds or inputs and medium or high yield potential are also important. Short duration is an important consideration for early wet season crops. The most commonly given reason for not growing the crop is damage from insect pests, followed by risk of crop failure, drought or natural disaster, and high cost of seed and other inputs. From the above observations, the following priorities for further research have been prioritized.