debor039

Our Chardonnay and some of the hybrid vines are in bud swell stage as of this week, and others are tagging along.  It looks like we will see bud break very soon with warmer temperature (but next week should be cooler). One of the diseases you need to consider this time of the year is Phomopsis cane and leaf spot.  It causes minor leaf spots, which is more obvious to our eyes, but the more important damage is caused by necrotic lesions on shoots and rachis. It also causes berry rot; however, it is not common with wine grapes because of our spray programs. Materials for black rot and downy mildew are often effective against Phomopsis. Thus, the fungicide coverage for these diseases is also working as management of Phomopsis, especially later in the spring and early summer. Some cultivars, such as Viognier and Seyval Blanc, are more susceptible to Phomopsis than the others. Phomopsis takes a while to establish in the vineyard. It may take 5-6 years for Phomopsis to become noticea...

Some shoots of our vines are about to reach the second catch wire, but I saw many that were still about 10-12 inches too. It looks like series of rain during the month of April drove developments of black rot and Phomopsis. Although it was not severe, I found several vines with leaf lesions of black rot, and a few vines with Phomopsis. Tan-colored lesions are symptoms of black rot. If you click the image, it will open a larger file where you can observe fruiting bodies (tiny black specks) within these lesions. It is a bit difficult to see, but, please note the holes on the upper picture (in the blue circled area). The lower picture shows more characteristic leaf spots of Phomopsis cane and leaf spot. For management tips, please refer to my  around bloom disease management consideration post.  Please remember that clusters will be susceptible to black rot from bloom to 4-5 weeks after bloom. Looks like Winchester area is expecting chances of rain on Friday, Monday, and the...

Our Chardonnay and some of the hybrid vines are in bud swell stage as of this week, and others are tagging along.  It looks like we will see bud break very soon with warmer temperature coming up next week. One of the diseases you need to consider this time of the year is   Phomopsis cane and leaf spot .  It causes minor leaf spots, which is more obvious to our eyes, but the more important damage is caused by necrotic lesions on shoots and rachis. It also causes berry rot; however, it is not common with wine grapes because of our spray programs. Materials for black rot and downy mildew are often effective against Phomopsis. Thus, the fungicide coverage for these diseases is also working as management of Phomopsis, especially later in the spring and early summer. Some cultivars, such as Viognier and Seyval Blanc, are more susceptible to Phomopsis than the others. Phomopsis takes a while to establish in the vineyard. It may take 5-6 years for Phomopsis to become no...

Our 7-yr old Chardonnay vines are in bud swell stage, and others are tagging along.  It looks like we will see bud break in a week or two. One of diseases you need to consider this time of the year is Phomopsis cane and leaf spot .  It causes minor leaf spots, but more importantly, it can cause necrotic lesion on shoots and rachis.  It also causes berry infection; however, it is not common with wine grapes because of our spray programs.  Materials for black rot and downy mildew are often effective against Phomopsis, thus, the coverage for these diseases are also working as management of Phomopsis, especially later in the spring/summer. Phomopsis takes a while to establish in the vineyard; however, once it is established, it is difficult to get rid of this disease.  Some varieties, such as Viognier and Seyval blanc, are more susceptible to Phomopsis than others.  Phomopsis tends to become noticeable as a vineyard gets older because of it l...

Our young Chardonnay vines are in bud swell stage, and others are tagging along.  It looks like we will see bud break in a week or two. One of diseases you need to consider this time of the year is Phomopsis cane and leaf spot .  It causes minor leaf spots, but more importantly, it can cause necrotic infection on shoots and rachis.  It also causes berry infection, which is not common with wine grapes because of our spray programs.  Materials for black rot and downy mildew are often effective against Phomopsis, thus, coverages for these diseases are also working as management of Phomopsis, especially later in the spring/summer. Phomopsis tends to appear as a vineyard gets older because this disease takes a while to establish in the vineyard; however, once it is established, it is difficult to get rid of this disease.  Some varieties, such as Viognier, are more susceptible to Phomopsis than others.  The fungus survives in canes and trunks that were infect...

We had a short shower event last evening; however, it was short and relative humidity did not stay high for a long time.  Thus, it was not a major disease infection event, except, probably downy mildew, since it only take about 90 min under optimal condition. Speaking of downy mildew, we have seen the beginnings of downy mildew in our experimental vineyard. Although our last application of mancozeb was only 10 days ago, rain events and humid nights probably promoted their development. At the beginning, you will see yellow circular discoloration on upper surface of the leaf.  Please note that sometimes insect can cause similar symptoms. However, if you flip over, you will see tiny white growth (please click the picture to access to a higher resolution file).  This won't happen with an insect damage. Please scout your vineyard, and if you see similar symptoms, it is probably a good idea to incorporate some of fungicides with kick-back activity.  In fact, we applied a p...

Our 5-yr old Chardonnay is about 50% bud break stage as of today. At this time of the year, the number-one concern is Phomopsis cane and leaf spot. They produce spores on old infected cordons and trunks during the spring, and they can infect tissues even if temperature during a rain event is in 40s. Only option we have against this disease is a protective application of fungicide, such as mancozeb, captan, and Ziram. A QoI fungicide such as Abound and Pristine are also effective; however, I would recommend keeping them for the later part of the season.  Since they can be active under cold rain event, my recommendation is to protect even when shoots are about 1-3 inches long. The decision to spray for Phomopsis also depends on the history of the vineyard. The vineyard with previous history of Phomopsis tends to carry the same issue year after year.  You are probably wondering about the risk of Phomopsis from this week's rain.  At our vineyard, we receive...