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Blemishes on the Road to Ripe and Juicy

Happiness is a perfectly ripe and juicy tomato however; many of those that I grow reach the table blemished by their journey to maturity. It is after all, a long trip from tiny seed to full ripeness – one filled with stresses that can leave marks and scars.

The earliest blemish begins in the flower when nighttime temperatures drift below 58F and pollination is less than perfect. Catfaces – those abnormal formations on the blossom end of the fruit are the result. If you are not growing organically, excesses of nitrogen and/or pesticides can also cause catfaces. My Oregon Spring Bush tomatoes produced several catfaced fruits this year thanks to those 40F nights in March – but they are delicious tasting in spite of their looks.

The other blemish commonly found on the blossom end can happen any time during growth and maturity of the fruit. Blossom endrot is not a rot at all, but damage caused by uneven watering or periods of dryness. Tomatoes grown in calcium poor soils are particularly prone to endrot however; proper and adequate watering is the easiest solution. I have an Oregon Spring Bush tomato growing in a large pot on the back porch and discovered how easy it is to get endrot in potted tomatoes – the daily water demands in summer are hard to meet.

There is another water associated blemish common to tomatoes, splitting fruit. Splitting in the skin occurs when the contents take in excess water and swell up. The water can be taken in through the roots or be absorbed through the skin. Overhead watering will guarantee split fruits, as will summer rains. The fruit will also split if the plants are over watered – so moderate, even watering and protection from rain will eliminate most splitting.

Hard water can also cause tomato blemishes. Pea sized and larger hail can cause serious damage to both the fruits and plants. It doesn’t happen often here, but one summer hailstorm can give you a blemished harvest. I try to get row covers tossed over the growing beds to cushion the impact, but am often not there soon enough.

Too much water, too little water and water that is too hard can all damage tomatoes, as can too much sunshine. Yup they get sunburns, or sunscald, and it doesn’t take long. Any die off in the shading foliage and the fruits are susceptible. To reduce sunscald reduce vine pruning in the summertime. I got sunscald this month when the row cover I was using as a shade cloth blew off one afternoon. We’ll eat them anyway, even though the sunburned spots will not ripen.

The last kind of cosmetic damage that I get comes from sharing my fruit with other garden dwellers – mice. A day or two before reaching perfect vine ripeness they are mouse ready. Sometimes I can eliminate the mice, sometimes I just harvest a day or two earlier.

So, even if your tomatoes have survived curly top, fusarium wilt, root knot nemetodes, bacterial spot, fungal diseases and the other fatal maladies on the road to sweet and juicy, you may still end up with blemished fruit. Fortunately the cause of most blemishes can be avoided with proper timing and cultivation, and if not you still have tomatoes with character on the table.

Till next time,

Darrol Shillingburg – June 2007
Doña Ana Extension Master Gardener



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