Red Blotch Research Articles

Treating `Primofiori' Lemons in Cold Storage with Intermittent Warming and Carbon Dioxide

Several intermittent 13C warming treatments were applied to `Primofiori' lemons (Citrus limon Burn) stored at 2 or SC. Fruit stored at 13C were treated with 10%, 2090, or 30% CO2 for 24 hours at weekly intervals. Reduction in decay and physiological disorders was best with two cycles of 2 weeks at 2C and 2 weeks at 13C and relative humidity >95 %. Under this storage condition, soluble solids concentration, pH, titratable acidity, and reducing sugars did not change relative to values at harvest, but the concentration of ascorbic acid increased and that of nonreducing sugars decreased in relation to harvest values. Carbon dioxide treatments did not prevent the development of alternaria (Alternaria citri Ell. & Pierce) rot and red blotch disorder, but effectively prevented the development of membranosis, rind pitting, and oleocellosis.

Occurrence of Red blotch of grain in Nagano Prefecture

Occurrence of Red blotch of grain in Nagano Prefecture

Dactuliochaeta glycines . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Dactuliochaeta glycines . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Glycine max (soyabean), G. javanica (= Neonotonia wightii ). DISEASE: Red leaf blotch or Pyrenochaeta leaf blotch of soyabean. Symptoms which appear on leaves, pods and stems are small dark brown circular to elliptical or occasionally irregular lesions, 1-2 mm wide with dark margins. With the advancement of infection lesions enlarge up to 2-3 cm wide but often coalesce to form large blotches covering > 50% of the leaf surface. Older lesions become necrotic, grey to dark brown in the centre with a dark brown or nearly black margin. Some lesions are surrounded by a chlorotic halo. Affected leaves become chlorotic and fall. In Ethiopia up to 75% defoliation has been reported in some varieties of soyabean. Initially it was reported that soyabean varieties with pale leaves were more susceptible than those with dark ones (Stewart, 1957) but recently it has been reported that soyabean with dark or light green foliage are equally susceptible (Hartman et al. , 1987). Lesions on Neonotonia wightii are generally circular and larger (< 4 cm diam.) than those on G. max . GEOGRAPHICAL DISTRIBUTION: Africa (Cameroon, Ethiopia, Malawi, Mozambique, Rwanda, Tanzania Uganda, Zaire, Zambia, Zimbabwe); Asia (India); South America (Bolivia). TRANSMISSION: By soil-borne sclerotia and pycnidia dispersed by rain-splash. Heavily infected leaves with sclerotia and pycnidia left on the ground may serve as inoculum for the next growing season (Hartman et al. , 1987). Primary inoculum is presumed to come from infected Neonotonia wightii which is widely distributed or from alternate hosts but the full host range has not been investigated. Longevity of sclerotia, pycnidia and conidia left in the soil has not been quantitatively assessed.

Biology and control of Polystigma ochraceum, the cause of almond red leaf blotch

Polystigma ochraceum is a major leaf pathogen of almond in Fars Province of Iran. Over a 4‐year study period it was found that ascospore discharge began at flowering and continued for 4–5 weeks. The maximum discharge occurred at petal fall. The incubation period was estimated to be 4–5 weeks under experimental conditions. Although the mature ascospores could produce short germ tubes in distilled water or water agar, the fungus could not be cultured or grown on conventional media from either ascospores, pycnidiospores or stromatic tissues under laboratory conditions.Of several systemic and non‐systemic fungicides evaluated under field conditions, triforine at 100–400 μ/ml was most effective. Other fungicides which significantly reduced leaf infection were, in order of efficacy, copper oxychloride (2000 μg/ml), copper hydroxide (2000 mUg/ml), Bordeaux mixture (10 000 μg/ ml) and mancozeb (2000 μg/ml). Carbendazim and thiophanate methyl (500 μg/ml) increased the level of infection. One application of the fungicide at petal fall and then two at 14‐day intervals were found to be effective in reducing the disease.

Method of assessment of red leaf blotch on soybeans used to evaluate cultivar susceptibility and chemical control

A field method to assess the infection of soybeans ( Glycine max) by Pyrenochaeta glycines, the cause of red leaf blotch (RLB), was developed and successfully used in three field experiments. The assessment method relates infection in the upper canopy leaves to a 0–6 logit scale. Three sprays of the fungicide, fentin acetate (tripenyltin acetate) at 0.6 kg ha −1 applied to plants of four selected soybean cultivars during reproductive growth restricted symptoms, thereby prolonging physiological development and increasing seed yield. Cultivars differed in their susceptibility to P. glycines and yields were larger in the less susceptible cultivars.

Threats to Soybean Production in the Tropics: Red Leaf Blotch and Leaf Rust.

Threats to Soybean Production in the Tropics: Red Leaf Blotch and Leaf Rust.

Prevention of Red Blotch in Degreened Lemon Fruit

Abstract Mature green lemon (Citrus limon Burm.) fruits are degreened commercially with ethylene to enhance yellow color development and improve marketing quality. This treatment often results in the development of a peel disorder called red blotch, a superficial reddish-brown discoloration, which may cover most of the fruit peel. We found that degreening at 30°C, instead of the recommended temperature of 25°, eliminated the disorder. Similarly, a predegreening treatment of dipping the fruit in the antioxidant ethoxyquin (“Stop Scald”) prevented red blotch development. The high temperature and the antioxidant may act on oxidative enzyme systems, which are apparently causative factors of the disorder.

Dactuliochaeta, A New Genus for the Fungus Causing Red Leaf Blotch of Soybeans

The generic name Dactuliochaeta is established to accommodate Pyrenochaeta glycines, the causal agent of red leaf blotch of soybeans and its synanamorph Dactuliophora glycines. The fungus is redescribed and illustrated from isolates originating from sclerotia on Neonotonia wightii or soybean (Glycine max) leaves or that were sieved from soil in Zambia, Africa. The genus is characterized by setose sclerotia which germinate to form mycelium and then setose pycnidia and/or pycnidia and sclerotia on their surfaces. The inner pycnidial walls are lined with ampulliform to lageniform, phialidic conidiogenous cells that often are periclinally thickened at the conidiogenous locus and bear uninucleate, hyaline conidia.

Effect of Red Leaf Blotch on Soybean Yields in Zambia

Effect of Red Leaf Blotch on Soybean Yields in Zambia

Red Leaf Blotch of Soybeans

Red Leaf Blotch of Soybeans

Epicoccum purpurascens . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Epicoccum purpurascens [Epicoccum nigrum] . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: plurivorous. DISEASE: The species usually occurs as a saprophyte or weak parasite although there are a number of reference to its occurance as a specific parasite. It occurs on a wide range of plants and plant material, human and animal tissue and processed foodstuffs. Generally regarded as a saprophyte or weak parasite but it has been listed as causing leaf spot of cassava (48, 2104), twig blight of Asiatic chestnuts (51, 1193) and because of its reddish-brown pigments (Β-carotene, torularhodin and rhodo-xanthin) it has been referred to as causing 'Red Kernel' disease of sweet corn (54, 2217), Red Blotch of rice (13, 538) and Brown Rot of apple. GEOGRAPHICAL DISTRIBUTION: Although new records of its distribution are constantly being published its range is probably world-wide wherever vegetation occurs. The CMI has material from all the major regions of the world and collections too numerous to list here. TRANSMISSION: Spores of the species are amongst the commonest components of the air spore (51, 1193) and have been frequently isolated from seeds of rice (53, 135), millet (53, 3004) and cereals in general.

Perspectives in neuro-ophthalmology.

<h3>Abstract</h3> Grapevine red blotch disease (GRBD) is an emerging disease caused by grapevine red blotch virus (GRBV). It is widespread in a majority of wine grape production regions in the United States and differential spread dynamics have been reported between the regions. In this study, we surveyed eight vineyard sites in southern Oregon over four years for the progression of GRBD incidence. The surveyed vineyards included five sites that were five years or older and three sites that were three years old. The disease incidence in the older blocks ranged from 2.81 to 58.78%; whereas in the younger blocks it ranged from 0.29 to 1.11%. Some of these vineyards implemented frequent disease scouting, removing, and replanting. The disease incidence in these blocks remained less than 5% over the survey period. However, in the vineyards that did not implement any roguing and replanting, the disease incidence increased by nearly 30-fold after three years. We analyzed the spatial distribution of the disease in vineyards surveyed in 2020 and found that the disease distribution is highly aggregated based on Spatial Analysis by Distance Indices (SADIE). In a separate study, we also tested the GRBV infection status of asymptomatic vines next to symptomatic vines to aid in the decision making process when roguing and replanting. Out of 410 asymptomatic vines, surrounding 41 symptomatic vines, only two tested positive for GRBV. Additionally, in 2020 and 2021, we tested the GRBV status on previously identified possible alternative host species, blackberries (<i>Rubus armeniacus</i>) and wild/feral grapes (<i>Vitis riparia</i>) collected from areas surrounding the four survey sites. We observed that GRBV was present in 10 to 70% of the wild grape samples in both years and 10% of the blackberry samples in 2020. However, the virus titer was low in blackberry samples and it was not detected in 2021 samples. These results indicate the potential importance of wild grapes as alternative hosts on GRBD incidence and spread in southern Oregon vineyards, while blackberry is unlikely to be an alternative host with epidemiological significance.

Red-Blotch of Hippeastrum

Red-Blotch of Hippeastrum