Grapes can be finicky in a lot of different ways. The environment has effects on the grapes, the weather has effects, etcetera. But what of pests and diseases, and what other problems may arise? Låt oss prata om det.
If you need to protect your plant during an early bud break situation (below 35 degree temperatures), set up a mister or sprinkler to continually mist your plants until the weather warms. While this seems counter-intuitive, the running water will prevent the buds from freezing again.
While this condition is most common in wine grapes, coulure can happen in other types as well. It’s important whenever possible to ensure that your vines have good conditions during the flowering stage to try to ensure that fruit set can occur.
Millerandage can be both beneficial or detrimental to winemakers. Some varieties of wine are actually enhanced by having some less-ripe fruit juice mixed with the ripe. Others are distinctly harmed, fouling the taste of the resulting wine.
Ensuring that your grapes are evenly fertilized during the flowering period will prevent millerandage, but inclement weather can make that difficult. På nytt, try to protect your vines during the flowering stage as much as possible.
There are a number of pests which prey upon grape vines. When growing grapes, it’s important to try to defend both the plant itself as well as its fruit. Let’s go over the usual problem pests.
Root Aphids
Bladlöss in general can wreak havoc on grapevines, although the common garden aphids are more a pest of the fruit than of the vine itself. Men root aphids of the Phylloxera family are a massive danger to grapevines, especially those used for wine grapes.
Root aphids will cause damage beneath the soil, making it hard to identify what the cause is. Plants lose their vigor, developing curling or withered yellow leaves. Fruits will be small or stunted. It can look very much like a nutrient deficiency.
To treat root aphids, you can use a diluted pyrethrin-based spray like Bonide Pyrethrin Concentrate eller PyGanic to drench the soil along the roots. This should kill off most of the hatched aphids. Retreat again every two weeks to kill off subsequent hatchlings.
Japanese Beetles
Another common pest is Japanska skalbaggar . These love to devour the leaves and young fruit on your grapes, and when you see one, it indicates that there’s likely eggs and grubs hidden in the soil waiting to hatch.
Neemolja is an effective preventative measure against Japanese beetles. While this does not outright kill the beetles, eating leaves with neem oil on them stops the larvae that hatch out of the eggs from reaching adulthood. It’s a slow process, but regular spraying will keep them away.
Black Vine Weevil
The larvae of the black vine weevil chew tunnels through your vine’s root system, causing severe damage and leaving the plant open to diseases. Adults will chew notches into leaf edges. These nonflying insects cause damage throughout their lifecycle.
Keeping adult weevils at bay can be done by spreading food grade kiselgur over all leaf surfaces and on the soil’s surface. While it needs to be reapplied if it gets wet, it’s a very simple way to deal with a bad problem. Beneficial nematodes will take out soilborne larvae.
European Grapevine Moth
De European grapevine moth can become another major problem. Not only do the larvae of this pest feed on flowers and fruit, but they transmit diseases such as botrytis cinerea. Faktiskt, a multi-year battle was waged in Napa Valley when this pest appeared, ending in 2016.
The larvae of these moths can be destroyed by using bacillus thurigiensis , or BT. Available as both a pulver eller a spray , this bacteria will poison the moth larvae and they will die off.
Parasitic Nematodes
Parasitic nematodes are another problem. These carry diseases such as grapevine fanleaf virus, and as they’re microscopic they are hard to locate. These live beneath the soil’s surface and cause root damage to your plants.
Defeating parasitic nematodes can be done in two ways. Beneficial nematodes can be introduced, and they will kill the parasitic ones as well as root aphids and other soilborne insects. Annat, a soil drench of diluted pyrethrins (see above) can be used to kill off all nematodes.
Fåglar
Till sist, the last pest isn’t a typical pest at all. Fåglar will happily eat Japanese beetles, European grapevine moths, and black vine weevils, making them beneficial most of the time. Tyvärr, they will also devour your fruit when it’s ripe!
Keeping birds at bay as your grapes ripen is usually your best bet. Use bird netting to protect your fruit from bird attack while allowing the birds free access during flowering and early fruiting. This ensures that the birds will eat your pests, but not your produce.
Sjukdomar
Some diseases which grapes develop can be beneficial in limited amounts. Dock, most are dangerous to both the vine and your eventual harvest.
Botrytis Cinerea
Botrytis cinerea is both good and bad. In limited quantities right before harvest, this fungal grey mold can be used to concentrate the sugars in grapes. Vid det tillfället, it’s often called the “ ädel röta ", as it can be beneficial to winemakers. But too much of a good thing can be a problem.
This fungal mold is what also causes fruit to rapidly decay after harvest, and so for raisins and table grapes, prevention is important. Dock, it’s tricky to fight. Using neemolja as a preventative can help, as can spraying a copper fungicide on visible fungal growth.
I’ve written a lot more about the noble rot and how it can be beneficial in our piece on botrytis cinerea, and I definitely encourage you to go read more about this disease and how to manage or treat it, as well as how the “noble rot” can be of use in grape growing!
Fusarium spp.
Fusarium , one of the primary causes of damping-off, can cause basal rot in grapevines. This is often one of the diseases spread by root aphids, and a couple Fusarium species are common: Fusarium oxysporium , och Fusarium solani .
As grape vines are nearly impossible to move once they’ve become established and there’s no treatment for fusarium, infected plants must be cut out and destroyed . Således, it’s better to prevent fusarium from taking hold .
Be certain to avoid overly-wet conditions in the soil, as that can promote fungal disease spread. Dessutom, consider adding beneficial mycorrhizae and beneficial bacteria to the soil. Our article on fusarium shares more methods of prevention as well!
Mögel
One of the most common issues when growing grapes is mjöldagg . Caused by fungal development on damp leaves, this mildew creates a whitish powder on the surface of leaves and can cause the plant to have difficulties with photosynthesis.
Tack och lov, powdery mildew is easy to treat. Regular applications of neemolja on all leaf surfaces will kill off any mildew spores in evidence and prevent further spread.
Black Rot
Svart röta is a common and potentially disastrous fungal disease of grapes. This condition causes some of the grapes in a bunch to shrivel and become mummy-like, and leaves and shoots will develop brownish lesions.
För närvarande, no organic measures are 100% foolproof for eliminating black rot. Dock, limited success has been achieved by maintaining dry leaves and stems , good pruning measures , and doing applications of copper fungicide on a weekly or biweekly cycle.
Some inorganic fungicides are available to treat black rot, so if you are comfortable with using chemical inorganic solutions on your fruit and vines, there are a number of types available.
Grapevine Fanleaf Virus
Till sist, there is the grapevine fanleaf virus . Spread by nematodes at the root level, this virus causes yellowing of the leaves and lowers fruit quality. It can be easily transmitted by nematodes between the plants, and there is no way to cure it.
Prevention is the key to this virus. If you find a plant showing signs of grapevine fanleaf disease, remove it entirely and dispose of it. Either do a pyrethrin soil drench or add nyttiga nematoder which attack root-feeding ones. Sterilize your pruning tools between cuts.
Thank you to the Cordi Winery in Live Oak, CA for allowing me to take a number of close-up photos of their Primitivo vines (and for having some delicious wines, too)! Också, thank you to Dez Fuhrman for sharing your great photos of vineyards in and around Lodi, CA!
When properly cared for, you can start growing grapes and have fruit for decades to come. Do you grow grapes, and if so, which varieties are your favorites? What do you do with your harvest? Share your vine knowledge and tales in the comment section!