The research was conducted in sub-district of Ciledug (Cirebon) with the objectives to study the infexiation and larvaal population development id onion armyworm. Spodoptera exigua (Habner) (Lepidoptera: Noctuidae), on shallots grown in lowland. Monitoring of egg masses and leaf damage were made at 3-4 days internal while of larvae at 1 week internal. Outbreak took place during the dry season of August-October 1995 when population density reached 0.8 egg mass and 23 larvae per hill, and subsequently all hills were heavily damaged. Throughout the rainy season of December 1995-February 1996, egg masses and larvae were difficult to find. Result of hand-picking showed that larval population during dry season was 78 times higher than those of rainy season. Larvae exhibited body color vartations. During the epidemics 80 percent of the larvae were dark whereas,during the endemics only 10 percent, the rest were light green. Level of egg parasitization was 0,9 percent coused by Tricogramma xp. (Hymenoptera; Trichogrammatidae) and telenomus sp. (hy menoptera; sceltonidae ), and larval parasitization 5.7 percent coused by Microplitis sp. (Hymenoptera; Braconidae), Euplectrus sp. and stenomesius sp (Hymeno[tera; Eulophidae), and Peribaea sp. (Diptera; Tachinidae). Low level of parasitization together with the abundance of food supply and dry season were believed to be the main foctors contributing to the population outbreaks. Hand-picking of egg masses and larvae conducted regularly, as practiced by the farmer group in the village of Dukuh wringin (Brebes(, should be adopted as a key activity for mitigating S. exigua infestation during dry season; and therefore, this practice should disseminated to farmers in other areas.
It has been known that phytoplasma inducing witches broom disease can infect various kind of leguminous plants in Indonesia, among others soybean. Information on the resistance of various kind of soybean varieties to the phytoplasma is still limited. Experiments were conducted to eveluate the resistance of ten soybean varieties/lines to the phytoplasma. The evaluation was carried out by inoculation method through Orosius argentatus Evans, with two days of acquisition feeding period, ten days latent period and two days inoculation feeding period. Observation was conducted on the presence of phytoplasma, incubation period, symptom and number & weight of seed. The result indicated that line Malang 3474 was resistant, Sindiro and Sriono were tolerant, while the other tested varieties/lines, i.e. Galunggung, Orba, Ringgit, Wilis, Malang 2999, Malang 2805 and Sicinang were susceptible
Biological and molecular variability among PStV (peanut stripe virus) strains isolated from various peanut growing areas in Indonesia was studied based on their pathogenicity and coat protein genes. Six strains of PStV causing different types of symptoms on peanut leaves were used to study biological and molecular variability among these strains. Biological variability of the PStV strains was evaluated based on their pathogenicity on peanut cultivars, Gajah and Landak. While analysis of the coat protein gene was used to study the molecular variability of PStV strains. Based on their pathogenicity, six PStV strains could be grouped into three groups, medium, strong, and very strong strains. Analysis of a coat protein gene showed the variability of the PStV strains were 0-2.1percent based on nucleotide sequence and 0-1.4percent based on predicted amino acid sequence. There was no correlation between biological and molecular variability.
Pratylenchus brachyurus (Godh) Filipjev. & Stekhoven is one of the importantplantparasitic nematodes that attacked root of patchouli and the causal of mot necrosis, growth retardation, reddish or yellowish leaf: A greenhouse study was conducted to evaluate the level of resistant of six patchouli cultivars, those were wide planted in Sumatera against P. brachyurus, and to determine the effect of population level of the nematodes on three dzrerent resistance patchouli. Six patchouli cultivars were inoculated with 200 nematodes& soil. Based on reproduction index the cultivar of Seulimum Putih, Pidie and Sidikalang known as susceptible ones Tapaktuan and Seulimum Merah was moderate resistant and Girilaya was resistant. Furthermore, the effect of population levels of P. brachyurus (0, 100, 200 and 800 nematodes& soil) on three patchouli cultivars showed that 200 nematodeskg soil population caused significant effect on reduced shoot and weight root and plant height on susceptible cultivars, howevec on the moderat resistant and resistant cultivar the signifcance effect occurred at 800 nematodeslkg soil. The reproduction factors on three patchouli cultivars were decreased with the increased of population nematodes level. me oil and chlorophyll content have been decreased on the infectedpatchouli cultivars atfive month afCer inoculation.
