Fertilizer application rates and recommendation for fruit trees

How to choose the right nutrients for fruit trees?

The term N:P:K usually means nitrogen (N), phosphorus (P) and potassium (K). These are so-called macronutrients. In order to remember them, you’ll have to learn the following saying: C. Hopkins Café Mighty Good Clean Mob Comes In (or C. HOPKNS CaFe Mg Cl MoB CuMnZn).

HOPKNS CaFe Mg Cl MoB CuMnZn represents 16 essential nutrients needed for plants. It denotes: carbon, hydrogen, oxygen, phosphorus, potassium (K), nitrogen, sulfur, calcium, iron (Fe), magnesium (Mg), chlorine (Cl), molybdenum, boron, copper (Cu), manganese (Mn), zinc (Zn).

How to understand which nutrients are deficient at a fruit tree?

Before letting the garden rest, soil sampling is carried out according to the recommendations of the laboratory or institution that will conduct agrochemical analysis. In Ukraine, there are institutions that offer sampling grids, for example: 1, 5, 10 or 25 ha/mixed sample. A sampling grid with sampling routes (diagonal or zeta routes are possible) is preliminarily created, a vehicle with a sampler carries out soil sampling (punctures to a chosen depth, horizons of 30 or 60 cm are possible) and a mixed sample is sent to a specialized laboratory for measuring the given indicators of macro- and microelements. It is also possible to do on one’s own, if you know how to do it, using a manual sampler and send it yourself. According to your request, the laboratory provides recommendations on applying fertilizers to provide your garden with one or another element of nutrition that is in short supply or in insufficient quantity.

Another way to find out what exact element isn’t enough at your tree, is conducting a plant analysis. If you are considering a specific tree, you need to pluck a few leaves from it and send it to the laboratory. If it is a large garden, then you’ll need to walk around and pluck leaves diagonally from different trees. Specialists will analyze them chemically and provide you with a result, containing the percentage of nutrients that your plants lack.

Can you see nutrient deficiency symptoms by looking at a tree?

In some cases, if you understand it quite well or if you’ve been through the agronomic training, the condition of the tree can tell where precisely the attention should be payed, but usually when you see certain symptoms, the tree has a problem coming right from the past. For example, if the tree is deficient of nitrogen, it’s shoot growth won’t be good enough and its growth and development will be stunted. The leaves will be of a light green color and small, they will turn yellow prematurely, starting from the edges. And, accordingly, if your plants are really dark green and actively growing, they have too much nitrogen.

Do you need to fertilize fruit trees in winter?

Fruit trees come out of dormancy when temperature begin to rise and therefore a metabolic reaction starts. They start using up the reserves they laid down last fall and stored over the winter in their trunks, roots, branches, and stems.

Therefore, in early spring, most of the growth comes from the reserves that are there in the tree. And that’s why you need to apply soil fertilizers about 4-6 weeks before flowering, as it is  the time needed for those nutrients to move into the soil and be reabsorbed by the tree when the soil temperature rises. And they use these reserves to initiate vegetative growth.

What fertilizers do fruit trees need in late winter or early spring?

At this time of the year, they need such macroelements as nitrogen, phosphorus, potassium. Among the mesoelements, some magnesium and sulfur will be needed if the plants are deficient of them and it can be observed now or could be observed during previous years. But mostly they need macronutrients. These are the nutrients needed in the biggest amount.

How do fruit tree feeding needs change in the spring?

The initial growth up until flowering uses the reserves that are there in the tree. Once the tree has flowered, it will start using all the nutrients you applied before it went dormant and during the dormant period itself. The roots take nutrients and distribute them all over the tree. And depending on the nutrient and the place of the most growth the nutrients will be delivered right there.

For stone fruits such as peaches and cherries, the first thing to open from the bud is the flower. In pome fruits, such as apples and pears, the shoot first begins to grow, followed by flowers. And that is why the distance between flowers is small. So really in the spring, to set fruit on stone trees, they really have to make sure they have enough stock from the previous year to support the initial fruit set of those stone trees. While apples, they also need to support shoot growth, and then they need to set flowers. Therefore, pome fruit may need a double dose of nutrients.

When may foliar application of calcium be necessary?

Calcium can solve what some call a “bitter pit” problem, a problem common to apple trees. It is common while calcium deficiency. The easiest way to solve it – is to spray the plant with calcium, starting after flowering and about every 10-15 days, using Wonder Leaf Mono Ca 14 (Ca – 14, N – 8, MgO – 2, w/w %).

What nutrients do fruit trees need in summer?

The crucial point when growing fruit trees is that we want fruit to set, isn’t it? Therefore, it is that exact time when micronutriients are compulsory to be applied for providing the fruits with nutrition. Initially, fruiting and growth takes place mainly due to cell division. So, all the cells divide. Later while vegetation, this occurs by cell expansion. So if there are a lot of cells that bind and divide early, right after flowering, then there will be more cells that can expand later, and so your fruit size will be bigger.

So the nitrogen level has to be high. Another important thing that is really critical during pollination is the boron level. That’s why you need a high level of boron in your fertilizer. And many commercial growers do foliar feeding with boron fertilizers in the fall or shortly after flowering. In order for your fruit trees to receive an element such as boron in sufficient quantity, we recommend using the following fertilizers: Wonder Leaf Pink (B – 20, w/w %), Wonder Leaf Mono B 11 (B – 11, N – 5 , w/w %), Wonder Leaf Mono B 120 (B – 9, w/w %).

What nutrients do fruit trees need in the fall?

The trees have gone through the growing season from budding to maturity and entry into the state of anabiosis. The fruit is being picked and all of a sudden you look up and think to yourself, “Well, our fruit has a bit of a cork and a bitter pit on it or it doesn’t look as expected.” Commercial growers often apply some microelements in the fall.

These microelements are only needed in very small amounts. These are boron, manganese, zinc and iron. In order to prevent manganese deficiency, we recommend using Wonder Leaf Mono Mn 11 fertilizer (Mn – 11, N – 2, SO3 – 10, w/w %). In order to prevent zinc deficiency, we recommend using Wonder Leaf Mono Zn 8 (Zn – 8, N – 5, SO3 – 10, w/w %). So often in the fall, after the fruit is gone, but before the leaves fall, commercial growers come in with foliar applications of microelements.