- Author: Help Desk Team
According to someone who knows such things, grapes are one of the most widely cultivated fruit crops in the world. Worldwide, there are over 10,000 different varieties, and whether one's interest is ambience, erosion control, raisins, jelly, table munchies, or wine, grapes nicely fit the bill. While grapevines are relatively hardy, they still need year-round care to be most productive.
There are extensive data regarding the growth and maintenance of grapes. Specific recommendations for when/where/how and why will depend upon some critical factors like soil type, location, sun exposure, grape variety, and more.
There are a few generalities that are helpful to home gardeners wanting grapes to be an integral part of their garden landscape.
- First, grapes need sun, full sun if possible, because less light results in lower fruit production, poorer fruit quality, and an increased incidence of certain diseases like powdery mildew.
- Second, grapevines can thrive in a variety of soil types, but good drainage is critical. Grape roots can be very extensive and deep, so ideally there should be 3–4 feet of soil above hardpan or rock layers. Table grapes tend to grow quite well on less fertile soils. On poorly drained soil, a large amount of well-decomposed compost should be incorporated before planting.
- Third, grapes need space, the amount of which is dependent upon the desired use of the fruit. Spacing between rows of wine grapes can be as little as 8 feet up to as much as 12 feet in very deep rich soils. Home grapes are often grown on arbors and in that situation one vine would require 50–100 square feet of arbor space. If the interest is only a few grapevines, then a space of at least 3 feet between plants would be a minimal requirement.
- Fourth, water requirements vary as a function of soil type and plant maturity. Water leaches quickly from sandy soils while it tends to collect in heavy clay. New vines should be watered weekly, sufficient to wet the soil 6–10 inches deep. Some recommendations suggest ½–1 inch of water/week for new vines. Five gallons of water spread over a 3' x 3' area is equal to about 1 inch of water. Established vines (over 2 years) can be relatively drought tolerant, but regular watering down to 12 inches will improve productivity. Once vines set fruit, watering can be reduced. Given that water use is so dependent upon a variety of factors like soil type, slope, sun exposure, it is difficult to prescribe a specific water regimen that is applicable to all.
Grapes can be grown from bare root preparations, usually with a fruiting cane grafted onto a disease resistant rootstock; this is probably the safest way to proceed. Alternatively, most grapes can be propagated as ‘own rooted' where a mature cane is simply placed in potting soil. This can be very successful, but the resultant vines are not disease resistant.
Canopy management is extremely important not only for optimization of fruit quality but also for management of potential problems, like powdery mildew. Shoot thinning is done primarily to reduce shoot congestion in the fruiting zone and to adjust flower cluster numbers. In addition to reducing the number of shoots emerging from the crown of the vine, the canes or the spurs, it is also important to strip leaves to increase light and reduce humidity in the fruit zone. However, in areas that can be very hot, it is important that there is adequate leaf coverage over the fruit to reduce sunburn or fruit shrinkage.
Proper pruning is critical to maintain good plant structure, optimize productivity and allow adequate vegetative growth for the following season. Unpruned vines will have excessive numbers of grape clusters and the vine will be unable to ripen the large crop. Pruning is done when the vines are dormant and just before bud break. Mid to late February is a good time in most of Contra Costa County. There are many approaches to pruning which depend, primarily, upon how the grapes are grown. This website has more information about pruning: https://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/grtrainprune.html
Like any plant, there are various types of diseases or conditions that can seriously impact grapevines. Some of the most notorious, such as phylloxera (an aphid-like insect that can destroy roots) or nematodes, can be managed by using disease-resistant rootstock stock. There are many other potentially serious conditions but in the home garden the most likely condition the homeowner will encounter is powdery mildew. This is caused by a fungus that does remarkably well in warm Mediterranean-type climates like ours. The mildew can affect leaves, stems, and fruit and grows on the surface of the affected plant part.
The best management of powdery mildew is prevention, which involves good cultural practices (e.g., canopy management for good air circulation) and, if necessary, fungicide applications. Fungicides can act as protectants, eradicants, or both. Protectants, such as sulfur, prevent new infections from occurring while eradicants like the oils (Neem, Stylet) can control as well as protect against infection. If conditions are right and/or if mildew is detected, protectants and eradicants should be used in 7–10-day intervals. These treatments should not be done when temperatures are near or over 90° F.
There are a number of invertebrate pests that can attack grapes, most notably thrips, leafhoppers, and mealybugs. UCANR has an extensive website that documents the various pests and their control. There are also a number of vertebrate pests that can cause considerable damage to the vines and/or the fruit including birds, raccoons, ground squirrels, gophers, rabbits, and deer. Exclusion techniques (netting, electrical fences, etc.) are the best management techniques for such pests.
For more information about growing grapes, see these websites: https://ipm.ucanr.edu/PMG/GARDEN/FRUIT/grapes.html https://ucanr.edu/sites/gardenweb/Growing_Grapes_in_the_California_Garden/
In spite of the potential problems identified above, grapes are hardy, resilient, and forgiving plants that not only have aesthetic qualities but also provide a wide range of culinary attributes. Give grapes a try—it's worth it.
Help Desk of the UC Master Gardeners of Contra Costa County (JRF)
- Author: Help Desk Team
When I first started growing tomatoes, I was reluctant and nervous about pruning my tomato plants for fear I would be doing it incorrectly. After 9 years of growing, I have learned that it is one of the best practices to include in your plant care. It is easy to do and produces better tasting and bigger tomatoes because you are helping focus the energy of the plant.
Here are a few simple tips for pruning your indeterminate tomato plants (determinate plants do not need to be pruned):
Removing suckers
- Suckers are the stems/leaves that grow out of the “V” junctions on plants. They grow fast and keep growing all season. These are best snipped off when they are small.
- Pinching can work as well but make sure you don't tear the tender stems. Before removing suckers wait until at least 2 leaves develop and pinch/snip just above that point.
Establishing the leader
- The leader is the main stem of the plant which starts near the ground.
- You may choose to allow additional leaders (or stems) to grow as well. There are advantages for each.
- Plants with two or more stems produce more tomatoes and greater/denser foliage which protects the plants from the sun. Tomatoes can sun burn!
- While the denser leaf canopy may reduce the incidence of black mold and cracking, it may also increase the incidence of other fruit molds such as gray mold.
- Plants with only one leader will bear fruit sooner but will ultimately produce a smaller total crop and may increase the incidence of some diseases due to the lighter foliage.
Topping your plants
- Pruning the top of your tomato plants once they have reached a desired height (usually about 5–6 feet) is perfectly acceptable and will push the energy down into the development of the fruit below.
- I find I need to continually do this all summer.
“Good to know” tips
- DO NOT Prune your plants when they are wet as this could spread diseases.
- DO prune off any bottom branches that are touching the ground as they can provide a direct vector for soil borne diseases to move onto the plant.
- DO prune off any yellowed or discolored leaves later in the season to keep the energy focused on the fruit.
- DO keep your nippers sharp and clean to avoid damaging your plants.
Below is a link to more information about growing and pruning tomatoes from the UC Master Gardener site:
Help Desk of the UC Master Gardeners of Contra Costa County (PDS)
- Author: Help Desk Team
Have you noticed burnt-looking blossoms and twigs on your apple, pear, or quince trees? This is likely caused by a bacterial infection, appropriately named fire blight. Fire blight can damage and even kill fruit trees in the Pome family and may affect other related species such as crabapple, ornamental pear, pyracantha, and toyon. It does not affect stone fruit, such as plum, peach, apricot, or cherries.
The disease is caused by a bacterium, Erwinia amylovora, which is most active during warm, wet spring weather. It enters the plant primarily through blossoms, but also through tender new shoots or bark wounded by mechanical injury or from strong hail and wind. It is spread by splashing water and pollinating insects, including bees. The pathogen is widespread in the environment but may not be much of a problem unless conditions are favorable. Older established trees can often withstand some fire blight damage, but young trees may be severely damaged.
The first sign of a fire blight infection may be dark and dried-up new shoots and young fruit, which soon turn black. You might also see watery, amber-colored droplets oozing from affected areas.
Fire blight may sometimes be confused with another condition, blossom blast, which also produces blackened flower clusters, but there are several symptoms characteristic of fire blight. On apples and pears, the tips of affected shoots develop a curved tip (‘Shepherd's Crook'). The scorched-looking young leaves and fruit do not fall off, but cling to the plant.
If a new fire blight infection is not removed in time, it spreads down through the wood, and bark cankers (areas of dead, discolored tissue) develop. If not removed, the infection in these areas persists from year to year.
Fire blight is not easy to control, but there are a few things you can do to manage this disease. Examine your trees regularly so you notice the first signs of a strike; the new shoots start to turn brown and droopy even before they become black. These shoots should be removed right away, cutting far enough below the infection to where no brown or discolored areas are seen. Use sharp pruners, disinfecting them between each cut. Use a 10% bleach solution or Lysol for disinfecting.
The disease becomes inactive during the summer and winter when bark cankers harboring the pathogen may be seen. These can be removed by pruning out diseased wood, at least 6–10 inches below the visible infection, or back to the branch connection with a larger branch or the trunk. If the canker is on a large limb or the trunk but does not girdle the branch, you can try scraping the bark away until no more discoloration is seen. Dispose of all infected material in the trash and not in the compost!
When fire blight is a problem from year to year, you can use a copper spray on the blossoms. This helps to prevent new infections but is not very effective if the pathogen is already in the tree. Such sprays can also cause russeting damage on the fruit.
When planting new trees, consider varieties that are more resistant to fire blight such as Arkansas Black or Cox's Orange Pippin. Unfortunately, many of our favorite varieties such as Pink Lady and Fuji, and most pears, are very susceptible. Tender new growth on a tree is more likely to suffer, so avoid practices that encourage this such as excess fertilizing and pruning. Also, don't irrigate while the tree is blooming.
This UC website provides more detailed information on fire blight and how to manage it.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7414.html
Help Desk of the UC Master Gardeners of Contra Costa County (SMW)
- Author: Help Desk Team
One of the comments we often hear as Master Gardeners is “My pepper plants grow but I get only a few small peppers or no peppers at all”. After a couple of frustrating years many gardeners stop growing peppers altogether. Peppers are a nutritional powerhouse as well as a rainbow of color, and they deserve a place in the garden. With attention to a few details, you can grow a “peck” of peppers and add a burst of color to your garden and your dinner plate.
While peppers are not hard to grow, they are quirky in a few areas.
The first quirky factor concerns cold soil temperatures at planting. Peppers do not like to have their roots in cold soil. Chilly soil causes peppers to go dormant Even when the soil warms, peppers may not fully recover, resulting in little or no fruit set. To prevent this, the minimum soil temperature for planting pepper is 70°F. The soil temperature should be taken early in the morning at a depth of 4–6” where the root ball is going to rest. Containers will reach 70°F first, raised beds will be a couple of weeks later, and in-ground beds will be the last to warm. Depending on how early you purchase your plants you may need to move them up into larger pots. One-gallon pots work well and will give the pepper roots plenty of growing space.
The second quirky factor is nighttime temperatures below 60°F. At this temperature peppers slow their development and at 55°F peppers may drop their flowers altogether. To prevent this, you can use polyethylene plastic tunnels, pulling the plastic over the peppers in the late afternoon to capture some additional heat when overnight temperatures are expected to be chilly. Instructions for DIY row covers and poly tunnels are in the link below.
The third quirky factor concerns heat. When the daytime temperature goes over 85°F, pepper pollen begins to shut down, at 90°F and above peppers often drop their blooms. To prevent this, we recommend putting shade cloth over your peppers on high temperature days. In addition to keeping the temperature cooler, the shade cloth is a great help in preventing sunscald on peppers.
Shade cloth comes in two types, woven and knit (lockstitch); we have found knit shade cloth works best and is resistant to rips, tears, and fraying. Shade cloth comes in percentages of shade provided. Choose one between 30%–50% for garden shading. You can find shade cloth in pre-cut panels or bulk rolls of various widths and lengths. To make sure you order the correct width, measure from ground level to ground level over the top of the hoops from side to side. Repeat this measuring process from one end of the frame to the other end of the frame to give the length. A simple frame using PVC pipe and 24” lengths of rebar (or pipe clamps) are quick and easy to assemble. This link will walk you through the process.
https://ucanr.edu/sites/ucmgnevada/files/333484.pdf
Although the following information is not vital, we have found these practices to be beneficial:
- Peppers are shallow rooted so a 2-inch layer of mulch will help keep the soil temperature cooler and the soil moisture consistent.
- Prep the soil with 2 inches of compost and a low nitrogen starter fertilizer; work gently into the top of the soil.
- Transplant peppers in the cool of the day, spacing them 18–24 inches apart to allow for good airflow. Peppers dislike having their roots disturbed; handle them carefully.
- Peppers do not tolerate overly wet or overly dry conditions. Keep peppers consistently watered especially during flowering and fruit set.
- High nitrogen feeding can result in low fruit yield. Place a side-dressing of aged compost or worm castings around pepper plants when the first flowers appear or feed with an organic low nitrogen fertilizer. Continue to feed lightly at 3–4-week intervals.
- Peppers appreciate additional mineral supplements of calcium, phosphorus, and magnesium as they are setting blooms.
If you pay attention to these three vital areas—cold soil, cold night temps, and high daytime temps—you will go a long way toward harvesting that “peck” of peppers. Take care to use the best practices and you'll be pleased with your results. The bounty of your garden will be a delight and treat for your friends and family.
Help Desk of the UC Master Gardeners of Contra Costa County (BHD)
- Author: Help Desk Team
If you have a history of “worms” in your apples, pears, or English walnuts, and have felt perplexed as to how to manage this problem, the very first step is to understand what is happening. When one understands that, the management becomes more understandable and approachable.
The “worms” are actually caterpillars, the immature stage of an adult moth. The life cycle is egg, larva (caterpillar), pupa, adult. The adult moth is mottled gray and small (½ to ¾ inch) and therefore hard to see and often goes unnoticed.
The adult female moth lays her eggs on or near developing fruit. The egg hatches and the caterpillar immediately will chew its way into the fruit where it lives and feeds. Entry holes are referred to as “stings” and typically exhibit a sawdust like residue called “frass”. If one sees a sting, the larva has already entered the fruit and is impervious to insecticidal sprays.
When it is ready to pupate, it will chew its way out and drop to the ground where it pupates in soil or leaf debris or under tree bark. After pupation an adult emerges and starts the cycle all over again.
The rate of development varies with temperature, proceeding more rapidly in warmer weather and climates. Depending upon the climate, codling moths can have two, three, and sometimes four generations per year. Our county has warmer climates inland and cooler climates by the coast. This means adult moths will start flying sooner and have more generations in the warmer areas and start flying later and have fewer generations in the cooler areas. Adult moths can start flying and laying eggs as early as March. The link below shows the approximate timing of the multiple generations.
https://ipm.ucanr.edu/PMG/PESTNOTES/pni7412-3.html
Codling moths can be difficult to manage, and a goal of 100% undamaged fruit may be unrealistic. A more reasonable goal would be to harvest enough undamaged fruit to meet your needs. In most backyard situations, the best course of action would be to combine a variety of the following non-chemical and low toxicity chemical methods early in the season.
Non-chemical:
- Pheromone traps (sticky traps laced with female pheromone to attract males) are not an effective management approach by themselves. They may be helpful if multiple traps are placed in a tree, but primarily they are used to monitor when adults are flying in order to time chemical applications. Traps can be purchased at most home and garden stores or online.
- Thinning your crop is important. The moths are most attracted to the place where two apples touch. Four to eight weeks after bloom, thin the fruit to only one per cluster, about every 6 inches.
- If you have thinned your fruit you may want to go one step further by “bagging” it. Although tedious and time consuming, placing bags over individual fruits early in the season, when the fruit is ½ to 1 inch in diameter, provides excellent control. The bag could be paper or cotton string. The link below provides a drawing of the bagging process. https://ipm.ucanr.edu/PMG/PESTNOTES/pni7412-2.html
- Beginning about six to eight weeks after bloom, and continuing every week or two throughout the season, check fruit on the tree for signs of damage (stings). Remove and destroy any infested fruit. Do not put the culled fruit in your backyard composting system, rather place it in green waste so it gets removed from your property.
- Since pupation takes place in litter on ground under the tree, keep the area continuously clean throughout the season, even though winter.
Low toxicity chemicals:
- CYD-X is a biological insecticide, a granulosis virus that affects only codling moth caterpillars. It kills by ingestion, therefore it must be ingested by the caterpillar prior to or as entering the fruit. To achieve this, it needs to be applied weekly beginning at the time of egg hatch. CYD-X is primarily available online.
- Spinosad is a biological insecticide, a bacterium that is toxic to insects in general. It kills by both contact and ingestion, therefore it needs to be applied at 10-day intervals beginning at the time of egg hatch. Spinosad is readily available at most home and garden stores.
- Adding 1% horticultural oil to either of the above improves effectiveness.
- Identifying the timing of egg hatch is key to the success of chemical applications. Egg hatch can be estimated by visually monitoring first stings or by using the UC Degree Day Calculator for codling moth https://ipm.ucanr.edu/calludt.cgi/DDMODEL?MODEL=CM&CROP=landscape
It is important to begin implementing control measures early in the season. The link below to the UC Integrated Pest Management website provides the detailed information you will need for implementation of your codling moth management program.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7412.html
Photo credits: Three photos above: Copyright UC Regents - photographer Jack Kelly Clark
Help Desk of the UC Master Gardeners of Contra Costa County (EDC)
