EC28-36 Spraying Tree Fruits (Revised March 1932)

The production of sound, clean fruit is unquestionably one of the major problems facing the modern fruit grower. Culture may be neglected and pruning delayed for a time but the omission of sprays for even a single season demonstrates their absolute necessity. This applies equally to the commercial grower and to the farmer or gardener who has only a few trees. Spray materials, equipment, management, schedules, insect pests and orchard diseases are discussed in this 1928 extension circular.

Effect of acibenzolar-S-methyl and Saccharomyces cerevisiae on the activation of Eucalyptus defences against rust

Tree defence mechanisms against the fungus Puccinia psidii were examined by comparing the activities of defence-related enzymes (chitinase, peroxidase and phenylalanine ammonia-lyase) of two Eucalyptus grandis x E. urophylla (urograndis) hybrids, previously classified as either susceptible to rust (VR hybrid) or moderately resistant to rust (C0 hybrid). Furthermore, the potential of disease control by artificial activation of host defences using either acibenzolar-S-methyl (ASM) or Saccharomyces cerevisiae extract was also investigated. Greenhouse inoculation trials revealed that the C0 hybrid had lower disease severity than the VR hybrid but following foliar applications of either ASM or S. cerevisiae extract treatment, disease severity (evaluated at 15 days after inoculation) was reduced in both hybrids. This enhanced resistance was associated with the induction of a hypersensitive reaction which appeared to be effective in controlling rust in both clones. The activity of all enzymes differed between clones and inducer treatment. The role of the defence-related enzymes in imparting resistance to eucalypt hybrids against rust is discussed.

Detecting sugarcane 'orange rust' disease using EO-1 Hyperion hyperspectral imagery

This Letter evaluates several narrow-band indices from EO-1 Hyperion imagery in discriminating sugarcane areas affected by 'orange rust' ( Puccinia kuehnii ) disease. Forty spectral vegetation indices (SVIs), focusing on bands related to leaf pigments, leaf internal structure, and leaf water content, were generated from an image acquired over Mackay, Queensland, Australia. Discriminant function analysis was used to select an optimum set of indices based on their correlations with the discriminant function. The predictive ability of each index was also assessed based on the accuracy of classification. Results demonstrated that Hyperion imagery can be used to detect orange rust disease in sugarcane crops. While some indices that only used visible near-infrared (VNIR) bands (e.g. SIPI and R800/R680) offer separability, the combination of VNIR bands with the moisture-sensitive band (1660 nm) yielded increased separability of rust-affected areas. The newly formulated 'Disease-Water Stress Indices' (DWSI-1=R800/R1660; DSWI-2=R1660/R550; DWSI-5=(R800+R550)/(R1660+R680)) produced the largest correlations, indicating their superior ability to discriminate sugarcane areas affected by orange rust disease.

Development and agronomic performance of common bean lines simultaneously resistant to anthracnose, angular leaf spot and rust

The common bean is affected by several pathogens that can cause severe yield losses. Here we report the introgression of resistance genes to anthracnose, angular leaf spot and rust in the `carioca-type` bean cultivar `Ruda`. Initially, four backcross (BC) lines were obtained using `TO`, `AB 136`, `Ouro Negro` and `AND 277` as donor parents. Molecular fingerprinting was used to select the lines genetically closer to the recurrent parent. The relative genetic distances between `Ruda` and the BC lines varied between 0.0% and 1.99%. The BC lines were intercrossed and molecular markers linked to the resistance genes were used to identify the plants containing the genes of interest. These plants were selfed to obtain the F(2), F(3) and F(4) plants which were selected based on the presence of the molecular markers mentioned and resistance was confirmed in the F(4) generation by inoculation. Four F(4:7) pyramid lines with all the resistance genes showed resistance spectra equivalent to those of their respective donor parents. Yield tests showed that these lines are as productive as the best `carioca-type` cultivars.

Antagonism of the two-needle pine stem rust fungi Cronartium flaccidum and Peridermium pini by Cladosporium tenuissimum in vitro and in planta

Selected isolates of Cladosporium tenuissimum were tested for their ability to inhibit in vitro aeciospore germination of the two-needle pine stem rusts Cronartium flaccidum and Peridermium pini and to suppress disease development in planta. The antagonistic fungus displayed a number of disease-suppressive mechanisms. Aeciospore germination on water agar slides was reduced at 12, 18, and 24 h when a conidial suspension (1.5 x 10(7) conidia per ml) of the Cladosporium tenuissimum isolates was added. When the aeciospores were incubated in same-strength conidial suspensions for 1, 11, 21, and 31 days, viability was reduced at 20 and 4 degreesC. Light and scanning electron microscopy showed that rust spores were directly parasitized by Cladosporium tenuissimum and that the antagonist had evolved several strategies to breach the spore wail and gain access to the underlying tissues. Penetration occurred with or without appressoria. The hyperparasite exerted a mechanical force to destroy the spore structures (spinules, cell wall) by direct contact, penetrated the aeciospores and subsequently proliferated within them. However, an enzymatic action could also be involved. This was shown by the dissolution of the host tell wall that comes in contact with the mycelium of the mycoparasite, by the lack of indentation in the host wall at the contact site, and by the minimal swelling at the infecting hyphal tip. Culture filtrates of the hyperparasite inhibited germination of rust propagules. A compound purified from the filtrates was characterized by chemical and spectroscopic analysis as cladosporol, a known beta -1,3-glucan biosynthesis inhibitor. Conidia of Cladosporium tenuissimum reduced rust development on new infected pine seedlings over 2 years under greenhouse conditions. Because the fungus is an aggressive mycoparasite, produces fungicidal metabolites, and can survive and multiply in forest ecosystems without rusts, it seems a promising agent for the biological control of pine stem rusts in Europe.

Variability in leaf rust susceptibility among peach cultivars

The aim of this work was to estimate the susceptibility of thirty-six peach cultivars to leaf rust caused by Tranzschelia discolor f. sp. persica. The incidence and severity of the disease as well as defoliation in peach trees of an experimental orchard of Parana Federal University of Technology, Campus Dois Vizinhos were evaluated on the growing seasons 2004/2005 and 2005/2006. Immunity to this disease was not observed in the studied cultivars. There was difference in leaf rust intensity depending on the growing season conditions. Cultivars 'Pilcha', 'Sinuelo', 'Chirua', 'Sulina', 'Eldorado' and 'Pampeano' showed tolerance to leaf rust, whereas cultivars 'Vila Nova', 'Fla 1372', 'Coral 2', 'Chimarrita', 'Della Nona', 'BR-1 ' and 'Guaiaca' showed high susceptibility.

Genotype-level interactions determine the degree of reduction of leaf rust on wheat by seed application of beneficial Pseudomonas spp.

Some bacteria have the capacity to reduce incidence and severity of plant diseases either by inhibiting the pathogen or by modulating the resistance response of the plant. Plants dispose of different resistance mechanisms that are influenced by the biotic and abiotic environment. The present experiments explored the effects of biocontrol strains of Pseudomonas fluorescens on the resistance of wheat varieties against brown rust disease caused by Puccinia triticina. Root inoculation with biocontrol pseudomonads reduced the disease severity on the leaves. The plant response depended on the genotype of both the microbes and the wheat varieties, suggesting a straight interaction at the molecular level.

Cedar Rapids Community School District, July 1, 2000 - June 30, 2001, June 30, 2002 & February 27, 2003

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Community Colleges for International Development Inc., Cedar Rapids Iowa, June 30, 2003

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KCCK-FM A Public Telecommunications Entity Owned and Operated by Kirkwood Community College, Cedar Rapids Iowa, June 30, 2003

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Kirkwood Community College, Cedar Rapids Iowa, June 30, 2003

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