|Nutrients||Water||Light or radiation (including intensity and day length)||Temperature||Air||pH||Toxic Chemicals||Mechanical damage|
|All species||Soil and plant tissue analysis are the most reliable basis for the design of a well balanced fertiliser programme.||Over and under watering combined with drainage of the growing medium are arguably the most common cause of problems with plant development.||Light intensity must be adequate since it is absorbed by the chlorophyll molecule, and converted to heat energy which drives photosynthesis. Low light intensity in seedling production facilities results in etiolation (stem elongation) and “soft” seedlings.||Germination speed and uniformity is temperature dependent, and may be completely inhibited by temperature extremes (which are specie and variety dependent). Sakata’s Range Test*, which tests the effects of a range of temperatures on the germination of a particular seed lot, enables the grower to maximise the potential of that lot. This test is available for hybrid tomatoes, onions, peppers, cabbage, cauliflower and broccoli. Disease resistance – expression can be affected by temperature extremes (partlicularly high temperatures). A lightning strike generates extremely high temperatures causing death of the entire plant population in the affected area and is often mistakenly attributed to biotic factors such as pathogenic fungi or bacteria.||The driving forces of plant growth are photosynthesis and respiration. The former requires CO2 and the latter, O2. An adequate air supply to both above and below ground plant tissues is essential. Raised beds are preferable to planting on the flat, since they improve soil aeration and drainage. In seedling production, it is important to avoid growing medium that has insufficient porosity (e.g. too fine) to facilitate adequate aeration.||pH levels should be close to neutral (too high and too low affects the availability of essential nutrient to plants).||Non-target exposure to chemical sprays can cause extensive damage to crops. This may occur as a result of spray drift, volatilisation or as residue from chemical appplied to a previous crop. Drift or volatilisation e.g. Hormonal herbicides (such as 2,4–D, dicamba and MCPA) cause plant abnormalities, even when exposure is minor. Volatile chemicals can do damage even when drift at the time of application is avoided. Traces of tannins in bark medium used for seedling production may affect germination of seedlings especially in hot weather.|
|Alliums (including Onions, Leeks etc)||Excessive nitrogen applications result in bull necks (large necks that are difficukt to cure) and soft bulbs with compromised storability. Sufficient potassium is also a significant factor affecting storability of bulbs.Although the application of Boron is sometimes indicated, great care should be taken not to exceed the suggested application rates since it can be highly toxic. Boron should be broad cast rather than applied in bands. Onions are very sensitive to Molybdenum deficiencies, which usually occur in acid soils.||Maintaining adequate moisture near the soil surface, at the onion stem-plate is important for root generation. Irregular water supply during the bulb development phase can contribute to the occurance of split skins and double centre bulbs. When drying or storing onions, the correct combination of ventilation, temperature and humidity control must be employed. If humidity is too low, bulb scales will crack excessively, and if it is too high there will be root growth, surface mould and rotting of bulbs. Avoid storing bulbs for extended periods when humidity cannot be controlled, although frequent turning will help to some extent in these circumstances.||Initiation of bulb formation is caused by exposure of the plant at a critical stage of development to specific day length. Deviation from normal temperatures and light intensities could result in early initiation resulting in smaller bulbs, late initiation resulting in bigger bulbs, or the plant not being at the critical stage of dev for initiation to occur at all. Since latitude determines day length, intermediate day length onions should only be planted south of the 28deg latitude (South of Welkom). Short day length onions can be used throughout South Africa, while long day length onions cannot be used at all. Sun scald of onion bulbs during drying (or curing) in the field, can be avoided by ensuring that onion tops provide adequate sun protection.||Pink Root Rot (caused by a fungus) is far more severe when temperatures are high. This even applies to varieties with a high level of resistance. The Sakata Range Test* is available for hybrid onions, and is used to determine suitable germination temperatures of a specific seed lot. The rate of bulb formation is temperature dependent, being most rapid at a mean temperature of around 21C. Cool temperatures along with other factors such as an imbalance in the N:K ratio can result in “bull necks” (thick necks that compromise storability).This is especially true of late varieties. Cold stimulation (vernalisation) of physiologically mature roots leads to bolting. Temperatures of 8 to 12C favours seed stalk formation, while high temperatures (approx 28 -31C ) can reverse bulb initiation, and is known as de-vernalisation. When drying or storing onions, the correct combination of ventilation, temperature and humidity control must be employed.||Raised beds are preferable since they improve soil aeration and drainage. When drying or storing onions, the correct combination of ventilation, temperature and humidity control must be employed. Since most bulbs are stored without cooling facilities, it is essential to have good ventilation.||The sensitivity of Alliums to low pH depends on the type of soil involved. The sandier the soil, the greater the sensitivity. Onions are very sensitive to Molybdenum deficiencies, which usually occur in acid soils.||Sprout inhibitors, which are applied to onions that are intended for long term storage, should not be applied when temperatures exceed 26.5C||When cutting tops, avoid cutting too close to the bulb as this reduces storability.|
|Beet (Beetroot, Swiss Chard)||Table beet is very sensitive to Boron deficiency, which causes canker (heart rot) in the roots.||Water stress exacerbates a boron deficiency. It is important to balance the water requirement so that the roots receive adequate moisture during the last half of their growth period, while the leaves stay dry enough to avoid fungal disease development. Irrigate early in the day to facilitate quick drying of the leaves. The storability of both beetroot and chard depends on the ability to maintain high enough humidity, cold conditions (close to 0C) with sufficient airflow to avoid heat build-up (but not so much as to cause desiccation).||Cold weather tends to stunt tops and roots. Prolonged hot weather adversely affects plant development. Soil temperatures above 25C retards or stops germination. They also causes an undesirable, strong flavour, white concentric rings and coarseness within the root. Cold stimulation (vernalisation) of physiologically mature roots can lead to bolting. The storability of both beetroot and chard depends on the ability to maintain high enough humidity, cold conditions (close to 0C) with sufficient airflow to avoid heat build-up (but not so much as to cause desiccation).||Raised beds are preferable since they improve soil aeration and drainage. They also facilitate better air flow in the leaf canopy. In windy areas, wind damage to young seedlings can be reduced by planting windbreaks (such as rows of rye or barley) which are removed once plants are established. The storability of both beetroot and chard depends on the ability to maintain high enough humidity, cold conditions (close to 0C) with sufficient airflow to avoid heat build-up (but not so much as to cause desiccation).||Beetroot is often harvested before roots are completely mature, when extra care should be taken to avoid mechanical damage. Injured roots are more susceptible to decay.|
|Capsicum (Paprika , hot pepper, sweet pepper)||Poor fruit set can be caused by over fertilizing (particularly with Nitrogen) The correct balance between various nutrients is essential. E.g. High nitrogen and low potassium results in excessively rapid growth which increases susceptibility to fruit cracking. Calcium deficiency is a contributing factor to the physiological disorder, Blossom end rot (which is often confused with a fungal or bacterial disease). Calcium is fairly immobile and its supply is easily affected by a fluctuation in water supply. Rapidly growing plants are more affected. High salt concentrations may also affect the uptake of Calcium.||Peppers are very sensitive to fluctuations in water availability (avoid wilting).||Sudden exposure of fruit to high light intensity (mainly the UV spectrum) can cause sun scald (sunken, pale tissue) that often becomes infected by secondary pathogens. This is more of a problem in open field production, and when foliage cover is reduced. Avoid over pruning of the canopy and use varieties with adequate foliage cover.||The Sakata Mayford Range Test* is available for hybrid peppers, and is used to determine suitable germination temperatures of a specific seed lot.Cold sensitivity: low temperatures have a detrimental effect on germination. Seed will not germinate at temperatures below 15C. Despite their need for warm growing conditions, peppers are also sensitive to high temperatures. Flower drop and/or poor fruit set is common at temperatures above 32C. Temperature extremes affect pollination. Wilted fruit has a compromised shelf life, so avoid harvesting in the heat of the day. Cold storage conditions should be maintained at a consistent 8.3C to 9C. Fluctuations lead to condensation and bacterial rotting, higher temperatures lead to ripening, and lower temperatures result in cold injury.||Peppers are very sensitive to low pH, and do best at between 5.5 and 7.|
|Carrots||Nitrogen in the form of ammonia applied when plants are young may increase the incidence of forked roots. Molybdenum (Mo) deficiencies cause leaf yellowing and total die-back in extreme cases. Low pH negatively affects the availability of Mo. Boron deficiencies are also a factor in soils with low pH, Solubor can be applied as a foliar spray` Insufficient levels of nitrogen can lead to bolting.||Extreme cold (heavy frost) before harvesting can damage leaves and retard growth. Cool Soil temperature (<10C) tends to make roots longer, more slender and paler than normal High temperature (above 30C) tends to result in inferior roots, increased disease susceptibility and sometimes bolting. Root flavour can become unpleasant. High temperatures (>28C) are also detrimental to germination, particularly when small seed sizes are used. Cold stimulation of physiologically mature roots can lead to bolting.||Raised beds are preferable since they improve soil aeration and drainage. They also facilitate better air flow in the leaf canopy. In windy areas, wind damage to young seedlings can be reduced by planting windbreaks (such as rows of rye or barley) which are removed once plants are established.||Molybdenum (Mo) deficiencies cause leaf yellowing and total die-back in extreme cases. Low pH negatively affects the availability of Mo. The application of Sodium molybdate on soils with low pH has been successful. Boron deficiencies are also a factor in soils with low pH, Solubor can be applied as a foliar spray`||Carrot roots are very sensitive to soil compaction which causes forked and stubby roots|
|Crucifers (including Brassicas, radish etc)||Boron deficiency: Crucifers and beets are more sensitive to deficiencies of this micro-element than other vegetables, with cauliflower being particularly sensitive (causes brown discolouration of the head) Magnesium is essential for the manufacture of chlorophyll (green pigment). A deficiency causes fading of the green pigment between veins that can be confused with mosaic virus. Calcium deficiency causes tip burn since it is required for normal cell wall development. It is exacerbated in periods of rapid growth. High yielding, vigorous growers are more susceptible.||Oedema : Caused by excessive water pressure, resulting in the rupture of cells. Cabbage is particularly sensitive (can lead to head splitting). Caused by excess soil water combined with low overnight temperatures / high humidity (reduced transpiration). Avoid excessive soil moisture when day-night temperature variations are great. Spring and Autumn heading varieties are more at risk.||Days to maturity can vary significantly from the norm as a result of temperature extremes Heat sensitivity: varieties that are not bred for hot conditions will perform poorly in hot weather. The Sakata Range Test* is available for hybrid cabbage, cauliflower, & broccoli, and is used to determine suitable germination temperatures of a specific seed lot.|
|Cucurbits (including squash, pumpkin, butternut, melons, and cucumbers)||Avoid too much nitrogen at the reproductive phase as this can lead to the abortion of flowers and fruit||Fruit cracking: Caused by excessive water pressure, resulting in the rupture of cells. Warm soil (which increases water uptake) combined with cold air (which reduces transpiration) increases osmotic pressure. Fruit with high sugar content has correspondingly high osmotic potential and is even more susceptible to fruit cracking. Precipitation during the pollination period reduces pollen viability. This reduces yields and can affect fruit shape.||Sudden exposure of fruit to high light intensity (mainly the UV spectrum) can cause sun scald (sunken, pale tissue) that often becomes infected by secondary pathogens. This is more of a problem in on dark skinned types, particularly when the foliage is reduced due to disease pressure. Hubbard squash is particularly sensitive. Grey skinned pumpkins such as Crown prince are more sensitive than white pumpkins.||Cold sensitivity: low temperatures have a detrimental effect on germination. Melons are significantly more cold sensitive than other cucurbits. Low temperatures reduce pollen release and bee activity resulting in poor pollination and lower yields. Fruit shape may also be affected by incomplete pollination and seed development. High temperatures encourage the development of more male flowers and fewer female flowers. At extremely high temperatures, female flower development may stop completely. This obviously has a significant effect on the yield. Warmer temperatures speed up the maturity of seedlings, which can easily become over mature.||Good ventilation is essential when storing cucurbits. Restricted air flow can result in the build up of ethylene and heat which reduces shelf life and causes yellowing of green fruit such as gem squash. Even varieties with good storability relative to other varieties (such as Gemini) may be affected.||Low pH <6.5 greatly increases susceptibility to Club Root caused by the fungus Plasmodiophora brassicae.|
|Lettuce||Calcium deficiency causes tip burn, since it is required for normal cell wall development. . It is exacerbated in periods of rapid growth. High yielding, vigorous growers are more susceptible.||High and low temperature extremes have an adverse effect on head quality. Germination is impaired by high temperatures. (Temperatures around 20C are ideal). “Cold grown” seedlings are generally better than “warm grown” seedlings because cell walls are harder. Hardening off of warm grown seedlings is essential especially when transplanting into hot conditions.||Avoid the build-up of toxic salts in hydroponic growing systems.|
|Tomatoes||Avoid over fertilizing (particularly with Nitrogen) Some varieties have an unusually well developed root system, which enhances their ability to utilise fertiliser and therefore makes them more susceptible to over-fertilisation. The correct balance between various nutrients is essential. E.g. High nitrogen and low potassium results in excessively rapid growth which increases susceptibility to fruit cracking. Calcium deficiency is a contributing factor to the physiological disorder, Blossom end rot (which is often confused with a fungal or bacterial disease). Calcium is fairly immobile and its supply is easily affected by a fluctuation in water supply. Rapidly growing plants are more affected. e.g……..High salt concentrations may also affect the uptake of Calcium. Adequate levels of Calcium and Magnesium help to reduce sunburn.||Over watering or excessive rain contributes to fruit cracking especially when day temps are high and night temps are low. Fluctuations in water supply affect the plants’ ability to supply Calcium to areas of rapid cell division which may lead to physiological disorders such as Blossom end rot.||Sudden exposure of fruit to high light intensity (mainly the UV spectrum) can cause sun scald (sunken, pale tissue) that often becomes infected by secondary pathogens. This is more of a problem in open field production, and when foliage cover is reduced. Avoid over pruning of the canopy and use varieties with adequate foliage cover.Adequate levels of Calcium and Magnesium help to reduce suceptibility to sunburn||The Sakata Mayford Range Test* is available for hybrid tomatoes, and is used to determine suitable germination temperatures of a specific seed lot.High day-night temperature variations (diurnal swing) are an important contributing factor to the development of catface on tomato fruit. Large fruited varieties such as Bravo are more susceptible to catface, particularly when planted early and late in the season Generally cat face occurs on the first trusses, but it can extend to subsequent trusses when conditions for its development are particularly conducive. High diurnal swing can also result in fruit cracks. Low temperatures increases susceptibility to zippering (a thin scar running from the stem end to the blossom end of the fruit). Too high temperatures (above 32C can affect pollination and may result in poor fruit set. It also reduces fruit firmness, and can render certain disease resistances (such as Bacterial Canker) and nematode resistance ineffectual. High temperatures may also cause the excess production of auxins resulting in reduce fruit size, and flower drop (abscission due to carbohydrate stress). Low temperature (below 25C) reduces germination speed and uniformity. Take note of the range test to avoid problems in the early season (eg Disco)||High doses of copper based bactericides during flowering can cause burning and abortion of flowers, and therefore yield reduction.|
|Turf grass||Turfgrass responds best to “spoon-feeding” i.e. application of fertliser little and often. Avoid over-fertilising with nitrogen relative to potassium. The application of trace elements is necessary. Iron deficiency, characterised by yellowing of the blades, is a common occurance.||Many irrigation systems deliver the same amount of water over the entire turf area, without taking the variation in water requirement between sun and shade areas into consideration. This results in either over watering of shade areas or underwatering of sunny areas. Almost all turf grasses (with the notable exception of kikuyu) must be sown into the top 5 -10 mm of soil, making them very vulnerable to dessication during the critical germination phase. The necessary high frequency/ low volume irrigations should be replaced with lower frequency/higher volme applications as the plants mature. Over -watering results in problems with soil aeration (see “Air”)||Most turf grasses require reasonably high light intensity to photosynthesise adequately. Although some species and varieties are better adapted to low light conditions, it is essential to raise the cutting height in shade areas, in order to increase the surface area available for photosynthesis, and also to accomodate the more upright growth habit that the grass plant adopts in order to adapt to low light conditions.||Both season and position must be taken into consideration when considering suitable sowing times. E.g. sowing cool season grasses in the hot months is possible in shady positions but not in the full sun.||Good ventilation of both the root system and the leaf canopy is essential. Compaction of the soil should be relieved by tining to facilitate the penetration of both air and water. When airflow is restricted (by walls, shrubs etc), the increased humidity places the lawn under increased disease pressure. Over-watering results in the air spaces in the soil being displaced by water, and the roots suffer from a lack of oxygen.||Sharp curves on greens should be avoided since the turning of the mower combined with sand (which acts as grinding paste) causes significant damage to turf. Blunt mower blades causes tearing of leaf blades & ragged edges (pale colour). Extremely high traffic levels can damage grass at a faster rate that it is possible for it to repair itelf (produce replacement blades). Measures such as laying of stepping stones or limiting the number of rounds on a golf course (aprticularly in stressful periods) must be considered.|
Disclaimer: This information is based on our observations and/or information from other sources. As crop performance depends on the interaction between the genetic potential of the seed, its physiological characteristics, and the environment, including management, we give no warranty express or implied, for the performance of crops relative to the information given nor do we accept any liability for any loss, direct or consequential, that may arise from whatsoever cause. Please read the Sakata Seed Southern Africa (Pty) Ltd Conditions of Sale before ordering seed.
Resistance: is the ability of a plant variety to restrict the growth and development of a specified pest or pathogen and/or the damage they cause when compared to susceptible plant varieties under similar environmental conditions and pest or pathogen pressure. Resistant varieties may exhibit some disease symptoms or damage under heavy pest or pathogen pressure. (HR = High resistance, IR = Intermediate resistance).
Experimental: This variety does not appear on the current South African Variety list, but has been submitted for registration. Recent version:Kindly contact Sakata or Area Representative for the most recent version of this Technical Bulletin.