- Author: Ben Faber
‘Hass' avocado fruit set, January 12, 2024.
I was looking for ‘Fuerte' fruit for harvest this winter and came across a grower who said that there was no fruit from last spring, but the tree is loaded with newly set fruit right now. This is in Santa Paula, 15 miles for the ocean. In the same grove there is also ‘Hass' fruit set going on. What is going on? It's too cold – day and night. Almost too cold for honeybees to fly and maybe too cold for pollen tube growth, even if there were pollination. Pollination is the movement of pollen from male to female stage flowers by a bug agent. Too cold for fertilization, pollen tube growth from the stigma down through the pistil to the ovule to start fruit formation.
Cold weather fruit set is often the condition for formation of ‘cukes', especially along the coast. These little bullet shaped fruit that are seedless can often form doubled fruit. We are sure of the actual cause of this occurrence but some varieties like ‘Fuerte' and in in some places like New Zealand have a greater occurrence of the fruit.
Stenospermocarpy is the formation of fruit after pollination and fertilization, but in absence of the seed, which has aborted for some reason. Somehow, the endocarp (the fleshy part of the fruit) continues to supply the necessary carbohydrates and hormones necessary for fruit development. So, there might be a lot of these cukes forming from this early set, or it may just not stick. The avocado is pretty clever, it keeps flowering through winter and spring until it has had a really good chance to set fruit that will hold to maturation.
Even the ‘Gordon' apple tree in my Ventura backyard is confused; it hasn't dropped its leaves this winter. This is not the winter that i was expecting.
- Author: Belinda Messenger-Sikes
During the holiday season, the only creatures you want stirring in your home are your family, friends, and pets. But as temperatures drop, and the rain returns, some pests may seek shelter indoors with you. Rats and mice can be problems all year but in the cold weather, they prefer the warmth of your home to being outdoors and you might see more in your home.
Pests invade homes for varying reasons during autumn and winter. Common outdoor species such as Argentine ants, Oriental (or Turkestan) cockroaches, sowbugs and pillbugs, springtails, and earwigs, may simply be escaping harsh conditions such as freezing temperatures or small-scale flooding. Some insects, especially true bugs (Hemiptera); such as boxelder bug, bordered plant bug, milkweed bug and other seed bugs, false chinch bug, and various stink bugs, naturally seek out dry, protected cracks and crevices to spend the winter. In the landscape, such sites may be beneath loose tree bark or deep within firewood piles, but structural gaps, cracks and crevices may be warmer, drier, and more attractive to these overwintering bugs.
It's generally easier to keep pests out before they become a problem than to try and get rid of them once they infest your home. Exclude pests by sealing up possible entry points around doors, windows, foundations, chimneys, roof joints, shingles, and vents. Install door sweeps and threshold seals to get rid of gaps under and around doors. If you have gaps around windows, you can close them with weather stripping and expanding foam or install new screens.
Clean up the landscape around your home so pests have fewer places to live and breed. Move wood chips and other organic mulches, and firewood piles away from your home's perimeter and entryways. Drain any excess moisture near structural foundations and entryways.
If you spot nuisance pests like boxelder bugs, earwigs, springtails, and centipedes indoors, they can be simply swept up, vacuumed, or taken outside. Other pests like mice and rats need to be dealt with differently.
Ideally, mice and rats should be managed before they get inside. Check the exterior of your home for signs of a mice or rat infestation including droppings, gnaw marks, feeding damage, and rub marks. For mice and rats, tight fitting lids on garbage cans and compost containers will keep these rodents from finding a food source near your home and eventually coming indoors. Thin vegetation between shrubs and buildings and trim back overhanging trees. Roof rats will use climbing vegetation to scale buildings and seek shelter. Seal any cracks or gaps into your home that are larger than 1/4 inch. Screen or block potential entrances under eaves or overlapping roof sections. Use sheet metal or 1/8-inch wire hardware cloth to keep out mice and rats since rodents can gnaw through softer material like plastic or wood.
Snap traps are the safest, most effective, and most economical way to manage rats and mice. You can place traps outside the home to catch rodents before they enter. You can also place them inside if you spot signs of them there. Be sure to use the correct-sized traps and place them in secluded areas along walls, behind objects, in dark corners, and in places where droppings have been found.
Keep pests from ruining your holiday fun by denying them food, water, and shelter in your home. For more details about specific pests and their management, see the UC IPM website https://ipm.ucanr.edu/PMG/menu.homegarden.html.
[Originally featured in the Winter 2023-2024 edition of the Home & Garden Pest Newsletter.]
- Author: Ben Faber
It wasn't supposed to rain this winter, but it did. The forecast was for La Nina which typically brings less rain and would continue the drought pattern we have had for the last three years. So with no rain, there is no need to spray a protective copper for brown rot or septoria, right? And with low prices for lemons, it pays to save money, right?
Well it did rain and we have had some problems. There have been problems, as well from the violent winds and the cold weather. According to Daniel Swain at Weather West, this was the coldest winter on record, even though the amount of time below freezing was low. The wet weather brought down trees and flooded fields, burying trees in some cases.
So we had unexpected rain, and violent winds and cold weather and that has led to concerns about the lack of copper applications. And there have been calls concerning symptoms on fruit that kind of look like disease, however in many cases it is not disease that is the ultimate cause of the damage. So let's look at some of this damage.
If copper had been applied, brown rot (Phytophthora sp.) probably would not have resulted from rain splash from the ground onto the fruit. There was a heck of a lot of mandarin and oranges that were lost in one case because of this.
In a few other cases, we have seen septoria fungal spot due to the fruit staying wet too long. Finding the black structures can identify this problem
But a lot of fruit spotting that might be associated with disease causing organisms, is actually abiotic, caused by non-living sources, like
Hail
Puncture
Oil spray damage
Cold, wet conditions that may have been on the edge of freezing.
So, it was a wet winter. Blustery and cold. It would have helped in some cases to have had copper on, but there were other causes of fruit damage than just all that wet. Some growers regret not having just put it on as part of the regular regime. This coming year, it's time to get regular again and make sure the trees have a protective copper cover. But if the rain and cold and wind and hail are back, there are some things that are a lot harder to provide protection for.
- Author: Ed Perry
For many in California, the backyard orange or grapefruit tree is almost a member of the family, and any negative change in its appearance elicits concern. One such change in appearance is leaf yellowing and drop that often occurs during the winter in citrus. Citrus leaves can remain on the tree for as long as three years depending on tree vigor, but disease, inadequate or excessive nitrogen fertility, excessive salt or born in the soil, poor irrigation practices, freezing temperatures, pest pressures and low light levels significantly reduce leaf longevity. Excessive leaf drop during the growing season is more likely to indicate a serious problem than leaf drop during the winter. Winter leaf drop normally reflects nothing more than a momentary swing in the natural balance between the natural elimination of old senescing leaves and their replacement.
Reduce winter water applications to citrus trees that have defoliated or that have a significantly thinning canopy. Trees like this require little, if any, supplemental irrigation. Even a mature tree with a full leaf canopy will require less than 10% of the water that it would require during the summer.
The best indicator of tree health for a defoliating citrus tree during the winter will be how well it produces the first flush of new growth in the spring. A decision to keep or remove a citrus tree based on tree health should not be made during the winter. Even trees that lose most of their leaves during winter are capable of replacing leaf canopies with the spring flush of growth, usually with little loss in fruit production. Trees that do not produce a vigorous flush in early spring may have a more serious problem. March is an excellent month to begin applying fertilizer to encourage new leaf growth and fruit production and to help keep an old friend of the farm or family backyard around for years to come.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
- Editor: Melissa G. Womack
- Author: Skylar Peters
Happy New Year from the statewide UC Master Gardener Program. Gardening in January can be a challenge with the cold weather and shorter days. However, January can be an excellent month for garden maintenance and preparing your landscape for spring and summer.
From giving your garden a makeover to planning for a vegetable garden, there are endless opportunities to stay active in the garden in January. What steps can you take to improve your garden this month? Here are a few tips to get you started:
- Watch weather reports. Accordingly, protect your plants from frost and other weather conditions. Cover them when necessary and adjust watering both for cooler temperatures and for seasonal rains.
- Don't forget about your houseplants. Make sure to keep your houseplants watered, as they tend to dry out from indoor heating during the winter months.
- Clear plants and debris. Clean out soggy leaves, broken branches and dead plants. Maintain unraked patches (if desired) and old rose canes for overwintering insects. Don't forget to pull out weeds.
- Keep your garden tools sharp and clean. Avoid rust and dullness and prepare for the pruning that takes place in January and February.
- Prune dead or damaged branches. Since January is the dormant season, it is the ideal time to prune. Prune your fruit trees while avoiding apricot and cherry trees. For more instructions on how to prune, check out this pruning guide.
- Start your vegetable garden indoors. Expand your growing season and start seeds, you can plant cabbage, chard, broccoli, cauliflower, and spring lettuce, to name a few. You can also start them in a cold frame or greenhouse.
- Plant flower bulbs. Get a jump start on planting flower bulbs this month, which can lead to a longer spring bloom!
- Plan your spring and summer vegetable garden. Design a garden plan now to prepare for spring planting. A great first step is to draw a map of your garden on grid paper and consider which seeds you want to plant and where.
January is a time of new beginnings, including in your garden. By preparing now, you can expect fantastic results in the spring and summer months.
Ask your local UC Master Gardener Program
January can be an unusual time in the gardening world, but we are here to help. For more gardening help and local county resources, click here to Find a Program. You will be redirected to your local county website and contact information. UC Master Gardener volunteers are available to help answer questions for FREE about your garden.
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