Many of the diseases or problems ailing the grapevines can be spotted in spring after the vines start growing. Infected vines commonly show delayed bud break, or develop shorter shoots or abnormal leaves. Reasons for these symptoms, however, can be many, and a more in depth analysis provided by a diagnostic laboratory is often needed to find out the actual cause of the symptoms. 

Fungal diseases caused by vine decline fungi (Phaeoacremonium and Phaeomoniella species) are often the culprits of delayed growth in spring. Infections caused by these fungi can remain silent for many years until vines become stressed due drought, overcropping, etc., which makes the symptoms to appear. In such stress conditions these fungi produce toxins that interfere with the vine’s normal growth. Vines infected by these fungi just don’t have the stamina to push the way the healthy vines do. 

Cylindrocarpon-infected vines also show growth delay in spring.  After closer examination and removal of the bark in the soil line, these vines can show brown/black cankers at the crown area. After so much of the vine’s water conducting tissues being compromised by the disease, there is not enough surface area to support the new growth. Depending on the amount of the injuries, these vines often collapse in the heat of the summer.

Canker diseases of grapevines caused by Eutypa and Botryosphaeria become easily detectable after the vines come out from the dormancy. Dead spurs or arms are often the first indication of the presence of these diseases. Eutypa can also cause curling or cupping of leaves, or shriveling of the berries. These symptoms are caused by the Eutypa-toxins that travel from the cankers into the sites of new growth.

A newly described pathogen of grapes, a Botryosphaeria-related fungus, called Neoscytalidium diminatum has been detected this year by AL&L Crop Solutions. The fungus was detected from young vines grown in Sonoma county. Affected vines had shown poor growth, and in some cases the vines had suddenly collapsed. Large cankers were detectable in the trunks of these vines. Neoscytalidium, which also causes disease on walnuts, was found first time on table grapes in Coachella Valley, in 2013.

Pierce’s disease can also be detected by an observant eye during spring. Keeping in mind that the symptoms are not the same as they are in the late season. In spring, vines that had been infected by this bacterium in the previous season, start showing delayed growth and chlorotic leaves. 

Some of the viral diseases of grapes can also cause growth delays and the infected vines can be spotted in spring. Leafroll viruses and vitiviruses have been often detected in underperforming vines in spring. Some clients also claim that Red Blotch infected vines had were developing shorter shoots. 

Early summer will also bring out symptoms of fan leaf and other nepoviruses. Vines infected with these viruses commonly grow leaves with yellow mosaic, or yellow veins, and sometimes leaves may be of abnormal shape. Since many viruses can cause these types of symptoms, spring testing can rule out whether any of these viruses are present.