A comparison of the in vitro and in planta responses of Phytophthora cinnamomi isolates to phosphite

Research in plant pathology often relies on testing interactions between a fungicide and a pathogen in vitro and extrapolating from these results what may happen in planta. Likewise, results from glasshouse experiments are used to estimate what will happen if the fungicide is applied in the field. However, it is difficult to obtain conditions in vitro and in the glasshouse which reflect the conditions where the fungicide may eventually be used, in the field. The aim of this paper is to compare results of the effect of phosphite on P. cinnamomi isolates in vitro and in planta

Sunflower Variety Trial Report

Variety selection is one of the most important agronomic decisions that sunflower growers make about their crop each season, especially in Vermont where the relatively short growing season limits available choices. Sticking with a tried and true variety is often difficult because new varieties are released every year while familiar ones are discontinued, and seed companies release new traits that may or may not influence yield. To help area farmers make the best decisions, UVM Extension conducted replicated variety trials at Borderview Reseach Farm in Alburgh, VT during the 2010-growing season. The trial evaluated fourteen varieties with varying maturity dates, seed sizes, and trait information, as listed in table 2. All varieties are non-GMO hybrids. The varieties Croplan 306 and Croplan 3080 were not treated with a seed fungicide or insecticide. All others were treated with the CruiserMaxx treatment package, which contains Thiamethoxam (broad-spectrum insecticide), Azoxystrobin (fungicide), Fludioxonil (fungicide), and Mefenoxam (fungicide)

Study on the curative and eradicant action of fungicide combinations to control late blight in potato

Commercial fungicide combinations were tested in the field for efficacy on foliar late blight caused by Phytophthora infestans in substitution of tin. When the first disease symptoms appeared, the tested fungicide treatments for late blight control were applied 3 times at 3-day intervals. The effect of the fungicide treatments on epidemic development, tuber rot and blight incidence and tuber yields were determined. Last summer late blight development was arrested in June due to high temperatures and lasting drought. August was characterized by rather low temperatures and high rainfall. These weather conditions were very favourable for the development of late blight. The foliar protection against P. infestans was comparable for all the tested fungicide combinations. The effect of combinations with dimethomorph + mancozeb (AcrobatC, 2.5 kg/ha) was less suppressive for P. infestans than the other fungicides tested. Lowest foliar disease severity was recorded in plots treated with fluazinam (Shirlan, 0.4 l/ha) + cymoxanil + chlorothalonil (Mixanil, 2 l/ha). Furthermore, highest tuber yield was noted in plots treated with fluazinam (Shirlan, 0.4 l/ha) + cymoxanil + chlorothalonil (Mixanil, 2 l/ha). The percentage blighted tubers fluctuated between 5 and 11 %. No fungicide combinations completely arrested epidemic development under the environmental conditions of the trial. However, fluazinam (Shirlan, 0.4 l/ha) + cymoxanil + chlorothalonil (Mixanil, 2 l/ha) controlled P. infestans most effectively

Regional spore dispersal as a factor in disease risk warnings for potato late blight: a proof of concept

This study develops and tests novel approaches that significantly reduce the fungicide input necessary for potato late blight control while maintaining the required high level of disease control. The central premise is that fungicide inputs can be reduced by reducing dose rates on more resistant cultivars, by omitting applications on days when conditions are unsuitable for atmospheric transport of viable sporangia and by adapting the dose rate to the length of the predicted critical period. These concepts were implemented and tested in field experiments in 2007 and 2008 in the North Eastern potato growing region in the Netherlands which is known for its high potato late blight disease pressure. Field experiments contained three starch potato cultivars, representing a range in resistance to potato late blight from susceptible to highly resistant, and a series of decision rules determining spray timing and incorporating an increasing number of variables such as: remaining fungicide protection level, critical weather, atmospheric capacity for viable transport of sporangia and the length of the predicted critical period. The level of cultivar resistance was used to reduce the dose rate of the preventive fungicide Shirlan (a.i. fluazinam) by default. A 50% – 75% reduction of the fungicide input proved possible in both years without adverse consequences to the crop or yield. The principles can be used in many decision contexts, but further work is needed to test and refine the methods before it can be used in practic

The Efficacy of Fungicide Application to Control Fusarium Head Blight Infection in Spring Wheat

There is a high demand for locally grown wheat for baking purposes throughout the Northeast. Currently, there is not enough grown in the region to meet this demand. One major obstacle for growers is Fusarium head blight (FHB) infection of grain. This disease is currently the most important disease facing grain growers in the Northeast, resulting in loss of yield, shriveled grain, and most importantly, harmful mycotoxin contamination. A vomitoxin called Deoxynivalenol (DON) is considered the primary mycotoxin associated with FHB. The spores are usually transported by air currents and can infect plants at flowering through grain fill. Eating contaminated grain greater than 1ppm poses a health risk to both humans and livestock. Fungicide applications have proven to be relatively effective at controlling FHB in other spring wheat growing regions. Limited work has been done in this region on fungicide application to spring wheat specifically to minimize FHB and ultimately reduce DON mycotoxin production. In April of 2016, the UVM Extension Northwest Crops and Soils Program initiated a spring wheat fungicide trial to determine the efficacy of a conventional fungicide application to reduce FHB infection on cultivars with varying degrees of disease susceptibility

Effect of cultivar, time of sowing and fungicide application on seed yield of cocksfoot (Dactylis glomerata L) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science in Seed Technology at Massey University, Palmerston North, New Zealand

Three New Zealand (Grasslands Wana, Grasslands Kara, Grasslands Tekapo) and two Japanese (Akimidori, Makibamidori) cocksfoot cultivars were sown in spring (23 September 1991) and again the following autumn (6 April 1992) at AgResearch Grassland's Aorangi Research Farm in the Manawatu. Seed was sown at 3 kg/ha with a 30 cm row spacing. Plot size was 1.2 x 3.0 m2, with each plot containing 4 rows. A randomised block design was utilised with 8 replicates of each cultivar for each sowing time. For each cultivar and sowing time four of the eight replicates were sprayed with propiconazole (125 g a.i/ha) on 17 November 1992 and 8 December 1992. Spring sowings outyielded autumn sowings by 150 to 482 kg/ha depending on cultivar The ability of the spring sown cultivars to outproduce autumn sown cultivars was due largely to their ability to produce a greater number of fertile tillers. Autumn sown cultivars failed to produce a large number of fertile tillers which lead to a reduced potential seed yield. This was further exaserbated by the fact that the floret site utilisation (FSU) of the autumn sown cultivars was lower than that of the spring sown cultivars. Cultivar Wana was the only cultivar able to produce a reasonable number of fertile tillers following autumn sowing. It was also able to double the number of florets/tiller compared to that of spring sown cv Wana, thus allowing it to produce a reasonable seed yield. Cultivar Wana produced 557 kg seed/ha from the autumn sowing, and cv. Tekapo 244 kg seed/ha, but yields for the other three cultivars were less than 100 kg/ha following autumn sowing. Spring sowing produced pure seed yields of 707, 566, 593, 383 and 307 kg/ha for cv. Wana, Tekapo, Kara, Akimidori and Makibamidori respectively. Apart from cv Wana, fungicide application to autumn sown plots did not significantly increase seed yield, and similarly no differences were recorded for spring sown cv Akimidori and Makibamidori. However fungicide application significantly increased seed yieid in cv Wana, Kara and Tekapo, the increases being 521 (+ 74%), 119 (+ 21%) and 564 (+ 95%) kg/ha respectively, even though the incidences of fungal pathogens was less than 1%. These seed yield increases were due to an increase in the green area of the leaves and stem. In cv Wana and Tekapo there was also a significant increase in FSU due to the application of fungicide. Following harvest stubble was removed and the area retained for another year and subsequent harvest. As the effects of time of sowing were considered no longer significant, the trial was run as one block of 80 plots, thus giving 16 replicates of each cultivar. For each cultivar, four replicates received one of four different fungicide (188 g ai/ha of terbuconazole) treatments; a nil application, one application at approximately 10% ear emergence, one application at approximately 10% car emergence followed by another at early anthesis and one application at early anthesis followed by one post anthesis (10 days after full anthesis). In the absence of fungicide pure seed yields produced were 1133, 1208, 915, 556 and 671 kg/ha for cv. Wana, Kara, Tekapo, Makibamidori and Akimidori respectively. Although once again the incidence of fungal pathogens was less than 1%, fungicide increased the seed yield of all cultivars. The best results came from two applications of fungicide, one at ear emergence and one at anthesis. The exception to this was for cv Tekapo which gained the greatest increase from one application at ear emergence. These treatments increased the pure seed yield by 29%, 15%, 23%, 43% and 19% for cv Wana, Kara, Tekapo, Makibamidori and Akimidori respectively. Different cultivars reacted differently to the application of fungicide, with fungicide significantly increasing the thousand seed weight of cv Kara. Tekapo Akimidori and Makibamidori, although it had no such effect on cv Wana. Fungicide application increased the FSU of cv Wana and Tekapo but did not significantly affect cv Akimidori, Makibamidori and Kara. Cultivars Wana and Makibamidori showed a significant association between green area and seed yield, but these relationships were not significant for the other three cutivars. There was a significant association between FSU and seed yield after fungicide application for all the cultivars except cv Kara. The most cost effect return for the application of fungicide was that of a single application at ear emergence. Keywords: Cocksfoot, Dactylis glomerata, rust, eyespot, propiconazole, terbuconazole, fungicide, sowing date, cultivar

The Efficacy of Spraying Organic Fungicides to Control Fusarium Head Blight Infection in Spring Wheat

There is a high demand for locally grown wheat for baking purposes throughout the Northeast. One major obstacle for growers is Fusarium head blight (FHB) infection of grain. This disease is currently the most important disease facing organic and conventional grain growers in the Northeast, resulting in loss of yield, shriveled grain, and most importantly, mycotoxin contamination. A vomitoxin called deoxynivalenol (DON) is considered the primary mycotoxin associated with FHB. Eating contaminated grain with DON concentrations greater than 1ppm poses a health risk to both humans and livestock. The FHB spores are usually transported by air currents and can infect plants at flowering through grain fill. Fungicide applications have proven to be relatively effective at controlling FHB in other spring wheat growing regions. Limited work has been done in this region on the optimum timing for a fungicide application to spring wheat specifically to minimize DON. In addition, there are limited studies evaluating organic approved biofungicides, biochemicals, or biostimulants for management of this disease. In April 2017, the UVM Extension Northwest Crops and Soils Program initiated a spring wheat fungicide trial to determine the efficacy and timing of fungicide application to reduce FHB infection on cultivars with varying degrees of disease susceptibility

The Efficacy of Spraying Organic Fungicides to Control Fusarium Head Blight Infection in Spring Wheat

There is a high demand for locally grown wheat for baking purposes throughout the Northeast. One major obstacle for growers is Fusarium head blight (FHB) infection of grain. This disease is currently the most important disease facing organic and conventional grain growers in the Northeast, resulting in loss of yield, shriveled grain, and most importantly, mycotoxin contamination. A vomitoxin called Deoxynivalenol (DON) is considered the primary mycotoxin associated with FHB. Eating contaminated grain with DON concentrations greater than 1ppm poses a health risk to both humans and livestock. The FHB spores are usually transported by air currents and can infect plants at flowering through grain fill. Fungicide applications have proven to be relatively effective at controlling FHB in other spring wheat growing regions. Limited work has been done in this region on the optimum timing for a fungicide application to spring wheat specifically to minimize DON. In addition, there are limited studies evaluating organic approved biofungicides, biochemicals, or biostimulants for management of this disease. In April of 2016, the UVM Extension Northwest Crops and Soils Program initiated a spring wheat fungicide trial to determine the efficacy and timing of fungicide application to reduce FHB infection on cultivars with varying degrees of disease susceptibility. This project is funded through an USDA NIFA Organic Research and Education Grant (2014-05379)

The Economic Value of the Precision Disease Management System for Anthracnose and Botrytis Fruit Rot for the Florida Strawberry Industry

The objective of this study was to examine the economic benefits associated with precision fungicide application system for Florida strawberry production. Given the weather and disease forecast system developed by the University of Florida researchers (Peres, 2010a , strawberry growers can potentially 1) reduce fungicide application rates during cool and dry conditions without affecting yields, thus reducing production costs; or 2) apply fungicide at the precise time of high disease pressure during warm and wet weather, therefore, decreasing disease development and spread, and increasing the yields and profits.fungicide application reduction, precision disease management system, strawberry, effect on yield, Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Production Economics, Risk and Uncertainty,