April chirps and sings
Splitting shells and seeds and blooms
April is a busy month in California gardens. With scorching summers on a not-too-distant horizon, flowers, weeds, and every other living thing are striding toward sunlight. Cool nights may hold this rampant growth in check for another week or two, but most gardeners have plenty of April garden tasks to keep them occupied.
Plum bud gall mite
As of January 2019, we have a new pest in northern California. Be on the lookout for abnormal growths, or galls, on almond, apricot, plum, pluot, and many other fruit and nut trees. These tiny eriophyid mites are only 1/100th of an inch long. If you have a 20x hand lens, you may be able to see them. They can be a translucent yellow, pink, white, or purple, with two pairs of legs up near the head. You are more likely to see galls on new shoots and fruit spurs that plants produce in response to these invaders. This new pest threatens tens of thousands of fruit and nut trees in California. If you happen to see this new pest on your trees, please contact your County Extension Office right away.
Tree Trunk Painting
If you didn’t whitewash your tree trunks (and exposed branches) in March, there is still time to provide this valuable sun protection. Trunks and branches that get too much sun exposure can be damaged, causing the bark to split and peel. This provides pests and diseases with easy access to your trees’ inner workings. A simple mixture of half water and half white interior latex paint is all you need to protect your trees from sunburn this summer.
This is also a good time to replace last year's sticky barriers. The protection from crawling insects cannot be overstated. Sticky barriers block those crawlers (and slugs and snails) from getting up into your fruit and nut trees. This is especially helpful when it comes to ants, which will protect and farm aphids. Over time, the goo dries, making it ineffective. Also, the tape tends to pull away from the trunk, creating an easy trail for pests. Gently remove the old tape, inspect the trunk, and apply a fresh sticky barrier.
Codling moth larvae can devastate apple, plum, pear, and walnut crops. The larvae pierce the fruit and burrow into its core, where it then feeds on the fruit, making it inedible. On apples, look for tiny dimples with a small hole in the center. These holes are usually filled with frass (bug poop). Trees should be monitored every week for signs of infestation. Infested fruit should be removed and discarded, to break the codling moth life cycle. Pheromone traps can be hung in isolated trees, but you need to understand that these traps attract codling moths to the tree. The traps are really a population monitoring device, not a control measure. Fruit can be bagged for protection, but this is a very labor intensive method. Kaolin clay application is an excellent organic control method. Heavy infestations may require the use of pesticides on the moths, before fruit is affected.
As flowers begin blooming, you can increase production by removing spent blooms. Take a look at buds further down the stem and clip just above a bud that points in the direction you want the new growth to go. Deadheading can help the plant structurally and allow for good airflow, as well as stimulate new flower development.
As difficult as it may be for gardeners to thin out fruit and young plants, it really is necessary for the optimal growth of remaining plants. April is the time to thin fruit on fruit trees, such as apricots, peaches, apples, pears, nectarines, and plums. Crowded fruit doesn’t get as big as it could and it encourages fungal diseases. Close-quartered fruit also provides great hiding places for pests. The best fruit grows from strong flower buds in full sunlight. The basic rule of thumb for thinning fruit is to leave one fruit per spur, with fruit 4-6” apart. Apricots, nectarines and peaches are normally thinned when the fruit is 1/2-3/4” in diameter. Nut trees do not need to be thinned. Seedling plants should also be thinned according to seed packet or other reputable information. This allows each plant to reach its full potential and it reduces problems with pests and diseases.
Spring rains bring moisture that can cause many fungal diseases. Anthracnose, brown spot, powdery mildew, sooty mold, and verticillium wilt should all be watched for and treated. Many of these conditions can be avoided with pruning that allows good air flow and irrigation that does not come from overhead. Overhead watering splashes millions of fungal spores onto uninfected plants, spreading the disease (plus, it wastes water through evaporation).
Irrigation & greywater
As temperatures rise, irrigation becomes more important. Container plants will begin to dry out and need to be checked every day. If the irrigation system wasn’t inspected in March, be sure to do it now. Greywater, from sinks, washing machines, and rain barrels can be used to irrigate ornamentals and lawns. I use water collected from the shower, as it heats up, to water edibles.
To add nutrients, reduce weeds, and to help retain moisture, nothing beats mulch. Wood chips and aged compost both make excellent mulch. You can request free wood chips from local tree trimmers. To stop weeds from growing, the mulch should be 4 to 12” think. I used to recommend a layer of cardboard or newspaper. That was until I learned that cardboard attracts termites and voles, and slows gas and water exchanges. Be sure to keep mulch at least 8” away from tree and shrub trunks, to avoid fungal diseases, such as crown rot.
If you have Navel orange trees, the crop will be ripening in April. Oranges left on the tree too long will dry out and become inedible. Instead, harvest the entire crop by the end of the month and you can make my new favorites, Cardamom Orange Marmalade, Orange Cumin Chutney and Spiced Oranges. Once canned, these delicious condiments make lovely gifts. You’ll want to be sure to save plenty for yourself - it’s that good! Valencia oranges will ripen during the summer and they make excellent juice. April is a good time to add nitrogen for orange trees. One-year old trees will need 1/10 of a pound of nitrogen, while mature trees need approximately 1-1/2 pounds. These amounts should be divided into three different feedings in April, June and August. Blood meal is an excellent source of nitrogen, without all the fillers.
QUARANTINE WARNING: MOST OF SANTA CLARA COUNTY IS UNDER QUARANTINE FOR CITRUS, DUE TO THE ASIAN CITRUS PSYLLID. CHECK THIS MAP TO SEE IF YOU ARE AFFECTED. ALSO, BE ON THE LOOKOUT FOR ORIENTAL FRUIT FLIES. IF EITHER PEST IS SEEN, PLEASE CALL THE PEST HOTLINE AT 1-800-491-1899.
Fennel, arugula, rhubarb, and asparagus provide many years of food production and April is a good time to plant. Fennel and rhubarb will take up a good amount of space, so be sure to keep mature sizes in mind.
Temperatures have finally reached the point when gardeners can plant most herbs, leafy greens, and other salad ingredients. Lettuce, spinach, bok choy, basil, parsley, cilantro and radishes can be planted every couple of weeks (succession planting) for a continuous harvest until temperatures get too hot.
Most vegetable crops can be planted in April, here in the Bay Area. Potatoes, bush and pole beans, corn, cucumber, summer and winter squash, and tomato seeds put in the soil now will begin their journey toward fruitfulness. Be sure to read packet directions for planting depth, spacing, and sun requirements for the best results.
One of the most important April garden tasks is to get rid of those weeds. Since they can go to seed faster than everything else in the garden, removing them out now will save you countless hours of work later on, in the summer.
Longer days of sun
Burst forth fruits and leaves
June is a busy month in the garden. Summer heat means irrigation and ants seem to be everywhere. Fruits, flowers, and mulch are the name of the game when it comes to June garden chores.
Ants & aphids
The bane of all gardeners, aphids are in full force in June. You may see ant trails in trees or curled leaves. Ants and aphids have a mutually beneficial relationship that may not kill garden plants, but they can carry diseases that will. They can also make fruit and vegetables inedible. Monitor for ants and aphids at least twice a week. If ant trails are seen, wrap tree trunks with tape and apply sticky barriers. This sticky goo will prevent ants form protecting and farming the aphids and halt the spread of many diseases. Aphid populations can then be reduced with a powerful spray from the hose. Adding plants that attract beneficial insects will also curb aphid populations.
Armored scale are parasites that suck the living sap from shrubs and trees. In June, these difficult to control pests are in a crawler stage that is easier to defeat. Monitor plants for armored scale infestations. Apply horticultural oil (not dormant oil) every month in summer to affected plants.
Bees are out in force, collecting pollen and nectar for their families (and pollinating nearly all of our garden crops). If you see a swarm, know that swarming bees are generally not aggressive or a threat, they are simply looking for a new home. You call contact your local Bee Guild or Master Gardeners for information on swarm collection. Honey bees continue to struggle and research on colony collapse disorder is ongoing. Recent findings have shown that systemic pesticides made with neonicotinoids are adding to the threat against native bees, but not honey bees. You can do your part to help our pollinators (and protect our honey supply) by avoiding the use of insecticides and pesticides when bees are present.
Blossom end rot
Are there brown depressions on the bottom of your tomatoes? This is caused by not enough calcium or irregular watering. Since most soils have adequate calcium, watering is usually the culprit. Without regular watering, the calcium in the soil cannot reach the plant. Mulching can help. Water tomatoes regularly, allowing the soil to dry out between waterings.
Blackened twigs & branches
If twigs and branches are turning dark or burnt looking, you have a problem. Generally, the damage starts at the tips and moves toward the body of the plant. This can either be dieback or fireblight. In either case, all you can do is remove the damaged tissue, cutting well below the visible infection and cleaning your clippers with disinfectant between each cut. Take a close look at the cut to make sure healthy tissue is visible. To reduce the chance of these fungal diseases attacking fruit trees in June, reduce or halt watering during the bloom and avoid adding nitrogen. Nitrogen stimulates new growth that is especially vulnerable to infection.
In California, most soils contain adequate nutrients for citrus growth, except nitrogen. One-year old trees will need 1/10 of a pound of nitrogen, while mature trees need approximately 1-1/2 pounds. These amounts should be divided into three different feedings in April, June and August. Blood meal is an excellent source of nitrogen, without all the fillers, or you can purchase a balanced product that contains zinc. Spread the fertilizer evenly over the entire root area and water in.
QUARANTINE WARNING: MOST OF SANTA CLARA COUNTY IS UNDER QUARANTINE FOR CITRUS, DUE TO THE ASIAN CITRUS PSYLLID. CHECK THIS MAP TO SEE IF YOU ARE AFFECTED.
Container planting is an excellent way to garden in small spaces and to add art and color to the landscape. However, June’s high temperatures can dry out containers very rapidly. To make matters worse, frequent irrigation can also leach out nutrients. It’s a dilemma. Gardeners can reduce these problems by using glazed clay pots, which dry out slower than unglazed pots. Dark plastic should also be avoided because it can get too hot and cook the roots. Good drainage is important, but you can help container plants hang on to water and nutrients by using potting soil, rather than planting mix. Also, be sure to get those pots off hot concrete. By creating even a little air space under the pots, you can help them stay cool.
June usually provides an abundance of fruit. If damaged fruit is seen, take a closer look. If the fruit looks chewed on, it’s probably rats or squirrels. Personally, I use Bobbex-R to deter these destructive, disease-carrying pests. My dogs enjoy helping out, too! I also use traps to kill rats. It’s a bit disgusting, but it works.
Does the fruit show stab marks? That’s usually birds. The only way to keep birds out of fruit trees is with netting or a tree cage. The netting is a royal pain to put up and take down, but it’s surprisingly easy to build a permanent tree cage. Most birds will only take a bite or two out of dozens of fruits, ruining a crop. Netting placed directly on the plant does not protect fruit near the netting. I also discourage birds by hanging old CDs in my fruit trees and mounting shiny pinwheels in various places. Breezes cause them to spin and reflect light, which seems to alarm the birds some of the time..
Spent ornamental flowers should be removed to stimulate new growth. When deadheading, don’t clip just below the flower. Instead, look down the stem for a leaf connection that shows bud growth. June deadheading is also a good time to prune for improved shape, structure and air flow.
Another common pest, earwigs are second only to slugs and snails in garden destruction. Even though they eat aphids, the damage they cause doesn’t balance out. Trap earwigs in moist, tightly rolled newspaper or cardboard tubes. Earwigs will gather in these bundles after their nightly feeding and you can toss them in the trash in the morning.
Fruit drop and fruit thinning
Don't be concerned if your fruit trees suddenly drop a majority of their blossoms or immature fruits. This normal behavior, called June drop or blossom drop, prevents trees from producing more fruit than they can support. To help your trees create the highest quality and best sized fruit, this is the time to thin fruits.
If you haven’t already, June is a good time to check irrigation systems for leaks. Drip systems should be flushed and emitters checked for clogs. This is also a good time to test to see where, exactly, sprinklers are spraying and where they are not. There’s no sense in wasting precious water in urban drool and the spray should never hit tree trunks.
Mulching is one of the best things you can do in the garden, especially in June. Mulching stabilizes soil temperatures, reduces weeds, and helps the soil retain moisture. Aged compost, placed on top of the soil, is mulch. Tree trimmings make excellent mulch and they can be acquired for free from tree trimming companies! As mulch breaks down, it adds valuable nutrients to the soil and improves soil structure. Just make sure that mulch is kept away from tree trunks and that it isn’t too thick. Generally speaking, a layer of 3 inches is just right. Too much mulch can interfere with gas exchanges.
If you haven't started already, June is an excellent time to plant those heat loving peppers, squashes, eggplants, and melons. Also, you can create an ongoing harvest by succession planting radishes, beans, and other determinant crops.
As roses give us their lovely June blooms, they may also put out suckers. Most modern roses are actually grafted onto hardy root stock that will not produce those lovely flowers. If new growth is emerging from underground, rip them out. Desirable canes, on the other hand, will grow out of aboveground buds and should be allowed to grow (assuming they won’t result in crossed canes or poor air flow. Black spot, rust, and powdery mildew are common fungal diseases of roses. Proper pruning can reduce the chances of these diseases occurring. Diseased leaves should be removed and discarded.
Be sure to put on your sunscreen, wear a hat, and keep those tools clean and sharp as you enjoy the garden in June!